Re: Ordering tank today - would like expert opinion on drilling plan !
Hi and thank you very much for your reply.  I have revised the pdf to remove the personal information.  I can also send you a JPG if that would be better.
<Either one... the jpg would be better>
I have some more questions about the 180g drilling plan if you have the time.  I thought I would need at least two 1.5" drains into my sump.  However, I have received some advice that I only want about 1000 gph through the sump and I think a single 1.5" drain should handle that flow, right?
<Mmm, better to have two... less noise, less possibility of real trouble should one become occluded, slowed>
Then I would need another 2000 gph through a closed loop if I want "decent" flow, but even that would note be quite 20X.  I just can't seem to get enough holes through the bottom of my tank with just a single end overflow.  I also want to avoid having the overflow go completely across the tank, visually I don't really want to see that from the sides.
Is it OK to have the closed loop intake drilled through the bottom near the far corner (away from the overflow)?
<Yes>
I'm not sure if you saw that one or not...
<Did>
I'm also looking at ways to have the closed loop intake come through the front of the overflow in two places (my overflow is getting crowded...)
My goal was the ability to have 3600 gph, but I don't think I can get that with one overflow and one closed loop.  I think it will end up requiring a powerhead in the tank or an additional closed loop somehow...  Where can I put more holes in this thing?  :)
<The other corner...>
Thanks so much!
Randy
<There are some fine "in place" pumps... look to Tunze's lines here, if you find you want more circulation. I think you will be fine. Bob Fenner>

Plumbing a 90 gal for up to 1800 gal/hr? - 7/8/03
Gentlemen, I hope your Independence Day was a BANG!
<A many entendre well wish, perhaps... at least for a manic ADDH adult <G>. Ha!>
I'm planning a 90 gal. reef and was considering running all of the flow (up to 20X) through a 36x12x16 inch sump to be housed in a shed outdoors here in sunny SoCal.  
<interesting... and have heard of this done by folks in your area. I recall the founder of Aqua C (Jason Kim) talking about doing this for his reef in San Diego area>
I'm trying to move much of the noise and evaporation outside and to avoid those unsightly powerheads.
<understood and agreed>
Does this sound like a "sound" concept?  
<indeed possible with your climate>
If so...... Can this be done through a single corner overflow box and how large?
<possible... although it will require some finesse to temper the sound. Do consider a half sized pump for the sump/return and perhaps a second pump on a closed loop on the tank to hedge your bets>
Finally, what size bulkhead and drain diameter?
<easy to figure, but too much to detail here per many sizes. Do decide on one pump versus two... and then check mfg specs (like Rainbow Lifeguard) for tolerances. 1" holes should only take 300 GPH each at most... but 2" holes may take more than 2X300GPH quietly. Also consider using the Durso standpipe modifications for a quieter overflow. See more info here: http://www.rl180reef.com/pages/standpipe/standpipe_menu.htm
Thanks!
<always welcome my friend>
P.S. I hear Anthony may be guest speaking our SCMAS club meeting soon.  I would love to purchase his autograph....especially if there is a book attached to it!
<I would love to come back to Cali soon :) Perhaps SCMAS could work something out with SDMAS (San Diego) or even DMS (Phoenix) to save on the airfare. I likely can stay at our good friend Bob Fenner's to save on lodging too. I'm easy <G>. I post my schedule at www.readingtrees.com and love to meet up with fellow fish nerds :) Especially our WetWebMedia friends! With kind regards, Anthony>

-AGA new style overflows-
This is for Kevin Sliech, if possible: <More than possible!>
Kevin:
I read an email that you replied to in the dailies on 6/24 (sorry, I am behind). I was wondering where you got your information on All-Glass' changes,
<Straight from the horses mouth, our regular tank-delivering wholesaler along with a pamphlet from AGA. I don't believe they're available yet, truck loads had supposedly left but we still continue to receive old-style tanks as they blow out their stock of them.>
and if you can point me to a link or elaborate further?
<It appears that AGA has yet to update their website this decade, so it will be little help to you. In short, the overflows (now called Megaflow or something fancy-pants like that) will be located on the back tank wall instead of in the corners. On tanks with a single overflow it will be centered on the left (I think left..) back half of the aquarium. On the 4' tanks that require two they will be each centered on a half of the back. On the 6' tanks, it appears that instead of centering them on two 3' sections on the back, that they're instead centered on the first and last 2' sections. I hope this makes some sense... I believe the drilled holes will be the same, but due to the shape of the overflows, there will be many more slots. This is great for folks like me who have all kinds of crap growing and blocking them. The accessory kit has the "Durso" modification to silence the gurgling. I hope this long winded response helps! -Kevin>

- Overflow Planning -
Hi Guys,
<Good morning, JasonC here...>
Great FAQs!  Unfortunately I didn't find anything pertaining to my situation (searched the internet as well).  I've been in the hobby for about 30 years, devoting the last 14 to reef aquariums.  I'm in the process of setting up a 375 gal. acrylic tank and have some thoughts about the overflow/surface skimmer I wanted to bounce off you.  I've always used over-the-top suction type overflows in the past and they've served me well (with proper maintenance), but plan to use drilled gravity overflows with this system but with a different twist as I'll explained below.  I didn't want anything inside the tank so I've ordered it without a built-in overflow.  I'm also installing it in a wall to be viewed from front and back so any overflow will be in the end (or ends?).  I have two ideas as follows:
1) Drill a series of holes (3/16 or 1/4 inch) at the desired water height in the end of the tank and build/attach the overflow box to the outside. 
<You'd almost be better off putting in a divider at one end that would act as a spill-over and having an overflow the width of the tank, then hide this portion by the wall, rather than trying to add something to the end of the tank.>
2) Install bulkheads (1 1/2 or 2 inch) with strainers at the desired water height and plumb to the sump. <Or you can do this - the quick and easy solution.>
Whaddaya think?  Any thoughts on the number of holes/bulkheads? <On one end, two, 1.5". On both ends, one each would be fine.> Whichever system, I'm thinking I should use both ends of the tank for overflow? 
<Ideally, but it wouldn't be difficult to use just one end - just add a slight slope to the tank so that gravity helps move the water to that end of the tank.>
Thanks much!  E. Russell
<Cheers, J -- >

- Overflow Planning, Follow-up -  
Hello again!
<Hello to you.>
Thank you for the reply.  Sorry for the resend earlier, just not patient enough some times.
Anyway......I would like some clarification on your earlier reply, if I may?  When I suggested installing large bulkheads with strainers through the side of my (acrylic) display tank at the water's surface as an alternative to an internal overflow your response of "quick and easy" leaves me to believe you don't think much of the idea (correct?). <No... what's wrong with 'quick and easy' - nothing wrong with bulkheads.> I'm interested to know your opinions on why you would or wouldn't use this method. <I think you misunderstood.> I really would prefer not to install bottom plumbed overflow boxes inside the tank and don't want to diminish tank space with an internal divider/spill-over on one end.  If you have any alternative ideas for a "through the side" gravity overflow/skimmer system I would love to hear them as well.  I'd also like your opinion on skimmer size.  The tank is a 375 gallon reef. I know what the marketing literature says but I'm curios to know if you think the AquaC EV-240 would be large enough or if I need to spring for the EV-400? <Think it would be worth it to have the EV-400.>
Thanks again for your time.  Eric
<Cheers, J -- >

- Overflow Design -
Hello Bob! - Please forgive the intrusion, I do normally post my questions to the "Crew" in general. <Well, it's JasonC here this time... hope you don't mind.> I'm looking for help with designing the overflow/s for my aquarium.  I'm in the process of establishing a new reef setup (seam rupture on previous 14 yr. old tank) that will be installed in a wall and viewed from two sides.  I awaiting the arrival of a 375 gal. acrylic aquarium from Tenecor (ships next week) which I ordered sans overflows.  I did this because my plan was (is) to utilize some type of "external" overflow system.  The dimensions of the tank are 96x30x30x3/4, of course the overflows will be installed on the end, or ends.  My idea is to drill a series of holes at the top two inches of the tank to function like the teeth on an internal overflow, and attach the overflow box (drilled for bulkheads - 2 x 2") to the outside of the tank.  If this sounds feasible to you, what would your recommendation be for the size of the skimmer holes? <It's kind of a sketchy plan... you will need to 'attach' the overflow box just as if it were part of the tank - with acrylic cement, otherwise it's going to fall off... you should consider just having this built onto the tank.> How many and how far apart (without compromising structural integrity)? <I'd go with 1/4-3/8" holes, as many as you want, not too close to any seam or edge.> What's the max flow I could expect through these holes? <Depends on how many you drill, but the number would be pretty high to match your expectations... perhaps 20-30 per end.> How big should the skimmer box be to handle the flow (say - max 2000gph)? <Well... drilling small holes isn't going to get you this high a flow rate unless you drill a lot of them - with standard bulkheads you need two to three 1.5" holes to reach a flow rate that high. Additionally, flowing this much water in and out of the tank is going to be very noisy... I would consider lowering the recycle rate in favor of some strong water movement within the tank via strong powerheads like the Tunze Stream Pumps.> Thickness of the acrylic? <I assume you mean for the overflow box... 1/4" would work - doesn't need to be heavy duty because it won't be holding much water at any given time. And... as I mentioned before, you will have to bond this to the tank with acrylic cement.> Have I missed anything >:-) <How about three large holes with bulkheads and strainers, plumbed directly to your sump?> If you think this is a bad idea my second choice would be to utilize an overflow design like Anthony describes in his coral propagation book. <I'd rather see you do this.> Saying that, what would be the measurements of this design? <The same as the width of your tank.> I would want to keep the dimensions to a minimum for aesthetic purposes. <Again, and I think we've discussed this design before... you should really be working with the people at Tenecor to help you realize this design rather than trying to augment the tank after its arrival. Add a couple of inches the length and this portion will be hidden behind the wall - this way you can have either a standard overflow on each end or perhaps something similar to Anthony's design. Any attempt to attach something to the side of your tank is ill-advised - if you have little or no experience with acrylic adhesives, you could potentially ruin your tank if you are not careful. If you've never worked with acrylic before, it's actually not that easy to make a five-sided box that doesn't leak - and you're talking about a four-sided box that needs to be attached to the tank.> If you have other ideas please feel free to expound. <My thinking here is that you should just keep it simple - drill two 1-1.5" holes on both ends - add bulkheads with strainers, and plumb these to your filtration system.> Any assistance will be greatly appreciated.
Respectfully,
Eric
<Cheers, J -- >

- Overflow Design -
I'm about to have some large tanks made and was wondering - is there any reason to build these tanks with conventional overflows, i.e., hole in the bottom of the tank with a stand pipe and overflow baffle? Would not a hole (or 2 or 3) in the back of the tank with a bulkhead and strainer located at the waterline accomplish about the same thing? <Indeed... as they say six of one, half a dozen of the other. Either would work fine.
Cheers, J -- >

New All-Glass Tank Overflows - 9/19/03
Thanks for your reply Anthony.  I have to know your opinion on the new all-glass tank overflows.  I do plan on upgrading my 90 gal reef to a 120 in a few months.  My question is to you do you approve (or like) the new design location of the overflow boxes on the reef ready tanks.  Would you get one of the new ones or get an old one, what are the drawbacks of them being in the middle back of the tank?   I don't know if I like how they put them in the middle of the tank.  Do you think I should get one of the older styles while I still can , that is if it will suit the reef keeper better than the new style.
<I'm grateful that they have addressed the issue in the hobby of having/providing drilled aquaria. My opinion of their old and new styles however, like any other commercial one I've seen, is that they are insufficiently drilled - lacking enough or large enough holes. What happens then is that aquarists often buy a properly sized sump/return pump for their display... but learn that the drains cannot handle them. So they throttle back the pump and need to add powerheads in the display... how ironic! And they are nearly as ugly, IMO, as those glass overflow towers <G>. My preference is to have overflow holes drilled high along the back wall... not the floor with a glass tower. I described modifying this with an internal horizontal overflow (more discreet and efficient) in my Book of Coral Propagation. We have several messages about it in our archives here at wetwebmedia.com too... do check them out with a keyword google search - toggle terms like "internal horizontal overflow" and see what you get. Hmmm... not sure if I've helped here or not. Holler if not :) Anthony>

Overflow Dilemma -
Dear Bob:
<Actually, JasonC today...>
It's been several weeks since I e-mailed you but I have another question that I have been unable to answer.  I have just about everything ready to go for a new 180 gallon marine aquarium (FOWLR) that I have been setting up. With your input I decided to purchase a Euroreef CS8-1 Skimmer as you may recall from my prior e-mails.  It will be placed in a 50-gallon sump in a stand beneath this aquarium.  My question deals with the tank itself.  It is from All-Glass Company and features two corner overflows (not the newer center-located overflows that are found on their newer tanks).  The Mega-Flow Overflow Kits that the dealer sold with this tank are a tight fit since All-Glass now uses the Durso standpipe system because of noise concerns, etc.  As you know, these feature a 1" bulkhead fitting in each corner and a 3/4" PVC return line.  The numerous postings on various websites regarding flow rates for this and other drilled setups has my head swimming!  The nice folks at All-Glass indicated that each overflow can handle a flow rate of 600 gph -- 1200 total for the tank.  The many letters I have read seem to present a different picture, indicating flow rates as little as 200 to 300 gph. <Nah... a total of 1200 GPH is about right.><<Mmm, nope. The earlier guesstimates are closer to reality. RMF>> I have a Mag 18 ready to use for the return plumbing to the tank.  I made this choice after calculating flow loss due to friction and head pressure through the 3/4" return plumbing.  The return line will use a 'Y' connector to split the flow path and eventually bend thru the 90 degree elbows near the top of the tank.  I estimated a return flow of about 820 gph -- or roughly 410 gph for each return line.  Based on the lower flow rate numbers from above (draining thru the 1" bulkheads) I am now concerned that this pump may be too powerful.  If this was your setup would you install a ball valve to control flow? <I'd install one for other reasons... being able to take the pump out to service it, etc. But again... I think you'll be fine with your pump selection.> I'm not sure how mag drive pumps can handle any type of back pressure, so I'm reluctant to do this. Or, do you believe these overflows can handle a Mag 18 without interruption? <No worries.> Just to note the Mag 18, according to the manufacturer, has a flow rate of 1200 gph at 5', and 825 gph at 11' (which is the figure I used).  Thanks for any advice you can offer.
Sam M.     
<Cheers, J -- >

- Overflow Calculations -
Hi Crew,
Would you kindly check my calculations/idea? <Sure.>
I am setting up a 75 gal non reef ready tank. As such, I need to use a hang on overflow siphon box (yuck). I really don't want to risk drilling the back unless you think it is worth taking the chance? <Not a chance you or I should take, but if there's no water in it I'd take it to a glass shop and have it drilled.> Anyway, I wish to set up a 15 or 20 gal sump/refuge. As the tank is in the living room I would not wish to have any flooding to explain to my wife! <Understood.>
If I keep the water level 2 inches below the top of the tank this would be about 7.4 gals short of overflow. If I then keep the submerged pump in the sump 6 or 7 gals below the sump high water level, then there should be little chance of the tank overflowing in the event of a siphon break? correct?? <Only if the water remaining the sump is not more than the 7.4 gallon margin of error in the top tank. Sounds risky to me... evaporation and top off will be your biggest issues.> The only worry would be the pump running dry and burn out? Which I could live with. <If that happened, you could lose everything in the tank.> Does this sound correct or am I missing something? <It 'sounds' correct but still more risky than I would be willing to tackle.> Also, when adding make up water, would I add to the tank or sump? Does it matter? <Doesn't matter.>
Thank you for your assistance. Happy Holidays.
<Cheers, J -- >

120 tank drilling 2/24/04
Hello Anthony,  I really like your idea with doing away with the "reef ready"  tanks with the unsightly overflow towers.  I plan on ordering a 120 from my LFS, I currently have a 90 dedicated to LPS only and do plan on keeping it that way (no mixed garden here, thanks to you, and the rest of the crew) ,
<excellent to hear!>
but I'm running out of room and plan on transferring the inhabitants to the 120 one of these days.  
<its one of my fave size/shaped tanks: 2X2X4 feet><<... four by two by two... LWH. RMF>>
I would like you're opinion on how I should have the tank drilled , I plan on ordering the tank from all-glass and having them drill the back walls at the top to accommodate 1 1/2" bulkheads that have strainers on them for the overflows to the sump, how does that sound?  
<exactly the way I'd do it>
or is there a better way that you would recommend?  
<spot on. And if it goes reef... then include a slender horizontal overflow sealed in front of the bulkheads for better skimming (see this in my Book of Coral Propagation or write back for the passage to be e-mailed to you)>
I was thinking 4 or 5  holes would do?  too many or too much?
<hard to say.. you need to determine what corals you will keep, what flow they will need, and if you want to/can run all of that flow through the sump (versus less holes plus a closed loop and second pump). No powerheads regardless>
Would  you have a better idea than drilling then with a 90 degree elbow and a strainer  on it to get this down to the sump to allow for more water flow (and a bigger pump)  or do I not need this as much with LPS ?  
<good skimming is needed with all truly>
Also I was thinking about drilling for the returns , should I do that or should I just run the piping up from the back of the tank?  
<that one is really just a personal preference. I favor up over the back and drilling less holes>
I was thinking about you're closed loop manifold, if that makes a difference.   thanks for you're help.  
<best of luck! Anthony>

120 tank drilling II 2/27/04
ok, thanks Anthony.  You mentioned that I should install a skimmer box in front of the bulkheads,
<not needed but helpful... much better skimmate>
I do have your BOCP, I looked at it, but how can I build this?? and how do I secure it to the tank??  
<its simply siliconed cut and seamed glass in a dry tank (or low drained tank)>
One more thing, I asked if I should go with 4 or 5 1 1/2" bulkheads drilled, you needed to know what kind of animals I intend to keep in there to determine if I should go with that or less.... well I am going to keep it a dedicated LPS tank, so how many should I go with here to provide the flow these plump, fleshy corals will need??  
<You really need to pick the corals by species name my friend... not just saying "LPS". That could mean Nemanzophyllia which suffers from even moderate water flow, to Hydnophora which requires remarkably strong water flow>
Also my sump should be able to handle the flow right?,
<yes... if designed well. Diffused flow to prevent excessive turbulence and bubbles being aspirated>
as long as my pumps can put it out right?  I could also lets say have 5 holes drilled and plug them if I don't need them, or if I someday want to add a closed loop pump to the system right?  thanks once again.
<all of these questions are really simple to see/understand if you'll take the time to visit some LFS shops to peep their functioning systems... better still, a local aquarium society with fellowship from local members to show you their tanks and systems. If none of this is possible, you can start or follow a thread with pictures on message boards to see how others do their systems. We are such visual creatures.. you need to see these systems in action and all will be so much clearer. Anthony>

- 135 Set-up/Plumbing -
Hi guys!
Thanks for your great site! I've poured over it as well as others gathering info and have a few questions for you regarding my set-up.
First off, this will be a freshwater tank which I will later turn into a reef. For now though I want to lay a good foundation to make the change easier and to have a great, clean, low maintenance and well set up tank.
The tank is 72L X 18W X 24H and came with an Amiracle wet/dry with a single drip plate (24x12x14). This tank has one back/center overflow (3 sides at 6" each)
I want to have at least 1350gph(10x) flow rate and am debating a bunch of plumbing, pump, filter issues:
1.. OVERFLOW: Considering my desired flow rate and current overflow box, what alterations to it would you recommend? <Get a second overflow installed? I don't know... not sure this single overflow will be up to your demands.> What's the max for this overflow and what diameter bulkhead should I use for it's downspout? <Uhh... you tell me, how big is that hole at the bottom of the overflow? I'm going to guess an inch - if larger, that is better, but if only one inch, then expect about 900 GPH max.><<RMF says 600...>> 1st concept: I've always wondered about the possibility of drilling intake bulkheads near the bottom of the tank and plumb them to the backside of the in-tank overflow box at the waterline - a sort of below the waterline overflow. My thinking is that this will aid in the removal of waste. <And water.> I'm not used to overflows and can't imagine effectively removing waste by only skimming water from the top. <Well... it's been working well enough for long enough that there are no significant changes in the design. I would caution you strongly about plumbing bulkheads well below the water line. Do make sure you have redundant valves and fittings beyond the bulkheads as a failure in anything attached to that bulkhead will result in draining your tank onto the floor.>
2.. RETURNS: For the returns I was thinking of using the manifold set-up. 2nd concept: create a spray bar along the back of the tank just above the sand level, elevating the rock structures just above the sand level with pvc stubs glued to the bottom of the tank. The idea being that this would help eliminate waste build-up and keep it waterborne. If I did this could I link a water level return between it and the pump to avoid back siphon during pump failure, would this work? <I think that in theory it will work - practical experience will tell the tale.>
3.. FILTER: How much additional sump will I need (something that I could later use as a refugium)? Do you think the single wet/dry will be ok for now (handle 1350+ gph?), what other additions or modifications should I look into? <Consider something other than a wet/dry if you plan on building a reef or refugium... look for a sump that is better adapted to this use. Wet/dries do not convert well to other uses.> (I know I'll need to get rid of the bioballs when I go reef.) <Actually, because the tank isn't set up yet, I'd recommend you just get rid of the whole filter and look for something else... don't wait to "get rid of the bioballs" - toss them now.> I want to keep mechanical filtration simple (such as drip plate or some other prefilter.) <How about a Berlin sump... simple micron sock to remove the waste.> I basically want to eliminate the need to vacuum and keep the tank as clean as possible. Suggestions please. <Cleanliness is only next to sterility in a marine tank. Sterility is not your friend or ally in marine husbandry.>
4.. PUMPS: I know you suggest Iwaki but I'm thinking (until I go reef at least) of going with the much more affordable "quite one" pumps. Unless you happen to suggest another better but still inexpensive pump. Would having two (redundant) pumps be overkill? <No.> I'm a little worried about depending on only one pump to run an entire system. What float switches do you recommend for preventing low sump/pump burnout? <Don't have any favorites here.>
Thanks for the time and help!
J
<Cheers, J -- >

Tank Modify
Anthony thanks for the help. Follow up to previous questions. I called the manufacturer of my 75 gal tank (ALL GLASS) and they said that the sides were not tempered glass so I think I'm going to have it drilled for overflow. One concern I have is a prefilter, should there be much of a problem if I have just a filter pad in the sump? any suggestions here?
<Emperor Aquatics makes filter socks that attach to PVC pipe and catch everything that drains down. Here is a link to their description http://www.emperoraquatics.com/mediafelt.html Emperor Aquatics calls them "Filter Enhancers Super Filter Felt Bags".
Another question is how many gph would a 1.5" bulkhead handle, I was told a 1" would handle @300 gph. I was thinking 2 1.5" bulkheads on each side of the back glass about 2/3 the way up... sound alright?
<I would put them as high as possible to fit the bulkhead in with the tank trim. I just had a 120 drilled to house three 1 1/2" bulkheads and I expect to run 2400 gph through them. This was an educated guess I my part from other people I had talked to. I will also be venting the drain pipe, so that when the water rushes in, the air pulled along will have a place to go.>
Since I don't want to "T" them together how should I make the flow to the sump...2 separate lines to the sump?
<Separate lines to the sump is best.>
Thanks again Bryan
<You are welcome. -Steven Pro>

Tank Modify
Bryan Here, Great info guys, w/out this site I would be lost. Trying to piece everything together on the modification of my 75 gal Tank. I want to run this by and see if it sounds good. For overflow I'm having the tank drilled for 2 1.5" bulkheads on both sides of the back of tank towards the top. 1-1.5" PVC/flex line down to the sump (separate lines/ emperor aquatics filter bags. In sump have mechanical and chemical filtration. Small submersible pump (@250 gph) to a small 20 gal refugium (raised higher than sump) contain a DSB of 4-5" of Carib sea special grade
<I have this sand in my 55 and have not been very impressed. I have seeded it numerous times, but the critters do not seem to like it and its coarseness allows detritus to settle between the grains of sand. Go with the Aragamax or other similar fine grain sand.>
and LR w/ a 1" bulkhead allowing for gravity to flow back to the sump. External Mag 9.5 for return flow to the main tank w/ check valve after pump. Possible "T" off to 2 PVC returns of 3/4",
<Start with 1" pipe off of the Mag-Drive and then at the T go to 3/4".>
to each side of tank for circulation/return w/ water blowing towards each other. 3 maxi jet 1200 PH in tank..2 at the back corners w/ flow to the middle front and 1 PH located more towards the bottom of tank. Aqua C remora hang on skimmer. 1/2-1" of special grade sand in the tank and LR added. Hope not to hard to follow. Any suggestions?
<See above>
My concern is placement of valves to limit flow in any area, and what to do to prevent an overflow of sump from the drilled overflow in tank if s/t happens to pump. Thanks again Bryan
<When you first fill the tank up, only add enough water to get the return pump to operate. After it is working for a few minutes, shut everything off. This will allow the water to back siphon down (simulated power outage). Once water has stopped, fill the sump. Now turn the pump back on. When it has reached an equilibrium, mark that water level. That is now your maximum fill level. Best of luck. -Steven Pro>

Tank modify follow up
<Anthony back again>
Bryan again, Thanks for the very speedy response Steven. Couple of follow up questions on earlier e-mail. I'm having trouble on how to tie in 3 overflow holes to the sump. Would some type aft" work?
<never use "tees" on an overflow... an accident waiting to happen>
Need a little help on this issue. Also in what part( or configuration) would the bulkheads be located on the back of tank. On each side and middle and how high on the tank should they be placed. 
<no on has ever demonstrated an advantage to any specific distribution of holes that I am aware of>
One last question Steven. Would going to 2 bigger bulkheads, say 1.5 to 2" work w/ as far as gph instead of 3 1" bulkheads. 
<possibly, but check fitting specs to confirm>
Thanks for great info Bryan. P.S Is putting a ball valve after each bulkhead a good idea or not?
<very dangerous...please don't...risks clogging/overflow and flow can be controlled on outflow side of pump with a gate-valve (restricting water that will overflow eventually. Anthony>

Tank Modification
Hey Bob, Bryan here.
<Hi Bryan, Steven here.>
I am in the process of redoing/upgrading my 75 gal tank. The last few days I've been coming up w/ some ideas. The main one I want to run by you is this. I was using a CPR overflow down to my sump. I would like to drill a hole or someone else) in the glass tank, attach a bulkhead with PVC and let gravity do the work, plus it would clean up the inside of the tank. I was thinking about a hole to fit 1" bulkhead w/ 1" PVC to the sump. Does this sound fine? Big question is how far up on the back should the overflow hole go. clear towards the top or about 2/3 of the way up going to use a Mag drive 9.5 for main pump. Last and most important question.. can my glass tank even be drilled, I believe it is tempered glass. Thanks again Bryan
<Tempered glass cannot be drilled. Check with the manufacturer as most do not make the entire tank out of tempered glass. Most times it is just the bottom or the long sides, but it varies by brand and model. Each 1" bulkhead can comfortably handle about 300 gph. I have and would recommend drilling 3 holes in a 75. -Steven Pro>

Over Flow Hello my fellows from WWM, you are like gremlins, the water touch you and walaa!!! more of you! this week I have seen at least 2-3 new guys!!! <Ha! we wish it was that easy :) Most of us were at a conference in Dallas this weekend but have since returned. Kudos to all those that helped and worked hard in our absence> Ok, my question. As you prophesized, my siphon is working bad, the last night I heard something like big bubbles, so (thanks to God) I woke up just in time to restore the siphon. The rest of my nigh was a nightmare dreaming about hermit crabs crawling in my bed... <heehee...> This morning I awoke with this resolution, convert my siphon in garbage and change my overflow.  <very good to hear!> In order to avoid drill the main tank, I don't have any place to put the fish, and other stuff, I design this device (I hope is clear enough) Please give me your advice. Carlos <it looks very interesting but I can't see how it will be done without draining the tank temporarily. Is this a gravity overflow on the shortened side wall? If so it looks very good to me! Best regards, Anthony>

Over Flow Hello my fellows from WWM, you are like gremlins, the water touch you and walaa!!! more of you! this week I have seen at least 2-3 new guys!!! <Hey we're also like Gremlins in shape and outdatedness! Except Anthony of course> Ok, my question. As you prophesized, my siphon is working bad, the last night I heard something like big bubbles, so (thanks to God) I woke up just in time to restore the siphon. The rest of my nigh was a nightmare dreaming about hermit crabs crawling in my bed... <You lucky pug!> This morning I awoke with this resolution, convert my siphon in garbage and change my overflow. In order to avoid drill the main tank, I don't have any place to put the fish, and other stuff, I design this device (I hope is clear enough) <Okay> Please give me your advice. Carlos <Very nice graphic. I like this design... would add a "tee" turned on end at the collective return (line dropping down to your sump) to reduce the noise of the overflow. Bob Fenner>

Overflow Box Project Hello all, I want to first thank all of you at WWM for the wealth of knowledge you have given me over the past week (I just found this site about a week ago, and wish I found it sooner). I have just built a 50 gallon acrylic tank 29 x 19 x 22, and I decided I wanted a sump, but would rather not build an overflow box in the corner (I would like to keep as much landscape as possible). I was reading about other overflow boxes hanging off the back w/ a siphon going from the tank to the box and down to the sump. I like this idea but I think I like the idea that the surface water spills over into the sump to break up that buildup on the water surface. I was planning on building an overflow box on the back of the tank, but instead of siphoning the water, the water would just flow into the box through holes in the back of the tank - please see diagram. The box would be permanently sealed on the back of the tank using acrylic cement. I haven't been able to find any ideas like this on your site and was wondering if you guys had any ideas about this. Any reason why this would not be recommended? Greatly appreciated <A good drawing, and workable design. I suggest adding an "aspiration" tube (a small diameter length of tubing down the larger overflow that will cut down "gurgling" noise tremendously)... and a larger "weir" (overflow cut out) about the slots you have pictured... to accommodate a troublesome blockage that may occur (a cut-out of the acrylic above the slots will do here). Bob Fenner> -James

Re: Overflow Box Project great! - thanks a lot for the quick response!!! -James <You are welcome. Please make it known how your project comes out. Bob Fenner>

Drilling Aquariums for Overflows
Hi Anthony... Hope you are well!
<cheers, Jenny! With hope you are too>
I sent an e-mail to you at your home address regarding further info I needed for my new tank. As I have not heard from you I guess you didn't get it or you have been to busy to check your mail there. Should I not have sent it there?
<my sincere apologies dear... I did receive it but have been buried in communications as of late. It has been a struggle just to keep[ up with our WWM mail. My apologies again>
I thought I would because it is the same subject I have been asking about and so thought you wouldn't want it on WWM to bore your readers with.
<not at all... we prefer to share all with the WWM readers for our mutual benefit and information exchange>
In short the LFS I'm getting the tank from say that the tank manufacturers won't do the spec he has sent them (which sounds like 6 holes of 53mm) without a signed waiver in case the tank fractures.
<not a surprise...they are all conservative... and look for ways to skim extra profits on "custom" orders.>
They say there must be a second 10mm back panel of glass siliconed to the first and also a  6mm safety panel in the overflow shelf you recommended (don't understand or see the need for the overflow shelf bit)
<I totally agree... the extra back panel is sensible... the internal piece is a sham>
This means 12 holes in all at a cost of approx. 22 USD per hole i.e. 264 USD just for holes!
<that's ridiculous... they should have just suggested 2 large holes instead and none of this would be needed. The number of holes is unimportant when an internal overflow box is used... that's what stretches the skimmed water and concentrates it. I did not/cannot recommend a specific hole size as I am not familiar with the available metric plastics/bulkheads in the UK. Still... you get the point from the diagram: any number of holes large or small to get the flow you need. Mfg specs for bulkheads will confirm flow ratings>
Can you just tell me a safe number/size of holes to drill to give me the flow rate of 2000 gph without the need for all this reinforcement they are saying is needed (6 holes sounds a lot to me anyway).
<six small holes (1"/25 mm) would not be a lot for this tank. But 2 or 3 larger holes (say... 40-60mm) would likely work as well>
If you can tell me this then I will tell them to do it and sign whatever they want just to get my tank!
<If the back reinforcing panel is not expensive, it is sensible and worthwhile. Too bad the extra hole drilling is priced so ridiculously. It sounds to me like this manufacturer does not have much experience with custom work. For this we are blessed here in the US, I suppose>
Anyway thanks a million for all your help and I promise not to bother you  with this one again. (notice I only said this one)
Thanks again - Jenny
<no bother at all, my dear... best regards! Anthony>

Great plumbing article
Hey folks,
Thought I'd pass this along. Advanced Aquarist's Online Magazine has posted its latest issue, with a number of good articles, including "An Engineering View of Aquarium Systems Design: Pumps and Plumbing," by Sanjay Joshi, Ph.D., Nathan Paden & Shane Graber. It can be found here:
http://www.advancedaquarist.com/issues/jan2003/featurejp.htm
I only scanned through it, noting that it has a lot of equations and tables, and is based on fluid dynamics and hydraulic engineering references. Should be great for those with technical circulation questions that I see pop up in the dailies from time to time. Hope you can pass this along to those who need it.
Later,
Jeremy M. Dawson, Ph.D.
<Thank you for this lead. Will post the link. Bob Fenner>

Can anyone guide me on a detailed, photograph rich
diagram on how to drill a hole in the bottom of an acrylic tank, install a bulk head and perhaps a stand pipe or something similar?  
<Hi Steve, I don't know of any photograph rich web pages illustrating this, but it is as simple as drilling a hole with a hole saw, installing the bulkhead and gluing/threading pvc pipe as the standpipe (as tall as the desired water level) and the plumbing from the bulkhead to sump. Make sure you put tape on both sides of the hole to avoid the acrylic chipping when the hole saw breaks through. Glue the fittings ahead of time so they have time to cure before you install them.>
I'm having SERIOUS problems with my siphon overflows failing once power comes back on after a power failure.  They lose their prime, and then the tank overflows as the return pumps water into the main tank from the sump, with no way for the water to return back to the sump via the P.O.S j-tubes.
<The other way to solve this is to put airline fittings in the top of your J-tubes (drill and glue) and connect them to venturi powerheads that will pull the air from the j-tube upon powering up after a power failure. This will restore the siphon and avoid floods. This is the second best way of doing this after drilling the overflows.>
I'll be doing this job today, as it is my only day off. I'm in hell. Thanks, Steve
<Hope this gets you to a cooler spot!  Craig>

Overflow modification
Hello again...
<cheers>
I have a question about one of the FAQ's I read in regards to the overflow described in Anthony's book.  The person wrote that he wanted to set his tank up without the overflow box on the upper back wall, just have the bulkhead holes with screens over them.  My question is, won't this keep the water level too low?  
<Well... it could be too low for aesthetics IMO and it would at that point have none of the benefits of the horizontal overflow described in my book. It would simply be a traditional bulkhead application. Those bulkheads  could simply have an elbow with a screen strainer turned upwards to raise the water level (and in fact give control over changing that level by swiveling the elbows higher or lower... some advantage there)>
If you have 4 1.5" holes about 3" to 4" from the top to the center of the hole, the water level will never climb much higher than
that, right?  
<correct if screen only are used... but elbows with screens can correct that (raise water level)>
If you do fabricate one of these overflows, I assume then that it should only touch the back wall,
<capturing the bulkheads yes>
hence your reference in my prior email to it being almost 48" in length.  
<indeed.. thinning the overflow water and improving proteins collected>
Then I don't have to worry about the tank bowing and the overflow separating from one of the walls, correct?
<correct... the flow of the long horizontal overflow is a tremendous support... prevents bowing>
Thank you!
<Best regards, Anthony>

Re: Almost made a big mistake (big tank plumbing)
First off I'd like to say that today was the first time I've visited your site and I'm totally blown away by the wealth of information offered.  I will definitely make this my first (and quite possibly ONLY) destination when posed with aquaria-related problems.
That said, I am building a 300gal "freshie" tank to house my ever-growing Clown Knife, and would like to bounce my ideas off someone who knows their schtuff.
My original plan incorporated a CPR Overflow Bow with two 1" outflow bulkheads rated at 1400 GPM.
<Mmm, do make this two overflow boxes... just in case one fails... you are likely familiar with how "frisky" Clown knives can be during the night... One unlucky swipe at the single box might knock it out of commission... the pump/s below will continue pumping, overflow the main tank, drain the sump/s...>
The 1" lines would run to two separate 30gal sumps, each containing a Quiet One Pump (an okay choice for freshwater I'm assuming).
<Yes... but please do check around re this pumps reliability... and consider other makes. The bulletin boards are great here for input. Ours: http://wetwebfotos.com/talk/>
The pumps(2) are rated at 750GPM at 4' head height, so with my head height of 5.5' I was counting on getting that down to under 700GPM per pump so that the CPR would keep up.
<Best to tie those sumps together (thru-hulls, pipe) in case of mechanical failures... am an old worry-wart with plenty of water damage clean-up experience...>
Now my problem: I've read over and over that siphon tubes (especially the CPR models) are nothing but trouble waiting to happen.  I am re-designing my setup to incorporate holes drilled into the back of the tank just below water level to allow gravity flow to the sumps (which will be easy as my tank is of mostly wood construction w/glass front).  Since the CPR box has two 1" bulkheads, and claims a 1400GPM flow rate, am I wrong in assuming that two 1" holes drilled in my tank will provide the same flow?
<Please oversize them... 1 1/2" inside diameter is much better... easier to arrange to not make a bunch of noise>
Also, if the holes are below the water line, and I make them too big, wouldn't that cause more water to enter the sumps than the pump could remove, causing sump overflow?
<Mmm, no... at least if you don't "overfill" the sumps... the amount of water "in play" is all you're concerned with. Start the pumps with the sump and main tank full, mark the sumps at the level they drain down to with the pumps on, and never fill the sumps beyond this level... the transit volume of water is the difference in starting, pumping levels>
Would using ball valves on the line to the sump and the line to the return head allow me to achieve a balance?
<Don't count on this... or even float valves... count on gravity and what sources of blockage, trouble you can anticipate. Bob Fenner>
Thanks for your help,
Brand Smith - Anderson, Indiana

Re: Skimmer Box / Overflow design
Hello WWM Crew!
I'm pondering an approach to get water out of my tank and into the sump without using a siphon-based design and without drilling the bottom of my tank.
I've attached a design in both PDF and JPEG format and I'm hoping you can give it a sanity check. The goals are to achieve a good flow and to minimize noise.  A couple of points I'm wondering about are:
- Is the (downward pointing) elbow in the skimmer box necessary,
desirable, or irrelevant? (I borrowed it from the Durso design without really knowing why)
<It's not necessary, but reduces sucking air sounds at water surface, esp. if the skimmer box has enough capacity to feed bulkhead flow. Box size should be large enough to accommodate flow, plus. The deeper in the box the bulkhead is placed, the less this is needed.  They sell bulkhead with screened intakes which could/should replace the filter/screen/light grid idea which will cause problems. Install a drip plate in the sump if you want this.>
- Is the tee with vented cap necessary, desirable, or irrelevant?
<Absolutely, this is where the venting/air will come from with a submerged bulkhead skimmer box/intake, so the water can drain into the sump.>
- Should the tee w/ cap extend above the top of the skimmer box teeth?
<It should rise above tank water level/skimmer box teeth by a few inches or water will drain out of the vent.....>
- Would fixing an air valve into the cap to allow adjustment of airflow be a good idea?
<Nope, you want a 1/4" hole that will allow air to enter and exit at will. The air must pass through this hole to equalize the pressure in the drain.>
- Should the outtake, tee, & drain pipe be the same size or should there be a reduction/enlargement somewhere?
<These can all be the same size, as long as they are sized for the desired flow rate.>
- Is having a pre-filter here a good idea? I like the idea of keeping gross objects out of the sump & drain line with the understanding that the pad or piece of foam will need to be rinsed frequently.
<Try a micron bag or drip plate in the sump instead.>
- If so, is a simple piece of light diffuser (egg crate) resting on small ledges inside the box a reasonable choice for supporting the filter media? Is this material generally considered to be aquarium-safe?
<Yep, as above.>
- Assuming a bulkhead sized for a 1.25" opening, how deep would you make the skimmer box and where in relation to the top of the box (waterline?) would you make the centerline of the outtake pipe?
<Many make these full tank depth. The depth is related to overall skimmer box size/capacity to feed the bulkhead water without sucking air at water surface or outpacing the box capacity. This is also true of bulkhead depth. The large the box and deeper the bulkhead, the better.  Some skimmer boxes run the full length of the tank. I would prefer a deeper box and bulkhead near the bottom. In the event of power outages, the water will stop siphoning at the bottom of the box teeth. You don't supply tank size or flow rate, just oversize box and plumbing to accommodate needed flow rate. Shop siphon type overflows to see what plumbing sizes/capacities they use.>
Well, that's it. Any other thoughts or comments you might have are
highly welcome. Thanks as always, Tim
<Looks good Tim, have fun!  Craig>

R: Overflow Question
Thanks!
Just to clarify, there won't be any no problems (noise or otherwise) with having the 3 2" bulkheads installed on the back wall of the tank, at the water line. With this configuration, no overflow will be set up. The water will free flow through the bulkhead into the vinyl type pipes behind the
tank, into the sump below.
<Should be sweet, esp. with vents (similar to Durso) just above the vinyl pipe fittings. A tee with riser and a drilled cap (1 - 1/4" hole) works great. I like ells in the tank, but they can introduce water noise.
Will 3 2" free flow piping handle 3000 gph?
<Sure. To double check look at the overflow rates of aftermarket boxes with 2" pipe. My vats use 2" overflows and they handle around 1400-1500 gph +/- .  Craig>

Re: Overflow via Durso vs. Back Wall....
Greetings to WWM,
If you were setting up a new tank which would you go with... Either 2 1.5" overflows w/Durso standpipes or a couple of bulkheads at the top back of the tank?
<Either will do the same thing. One is less expensive than the other unless you use overflow boxes in which case they are roughly equal in cost/flow/noise, depending on size (of box and plumbing/bulkheads), depth (of overflow box and how far, if any distance, the water falls into the boxes.>
Rather than personal preference I am looking for the configuration which will A. minimize the amount of overflow in the case of power outage and B. minimize the amount of noise.
<This depends on how the boxes are set-up and the height of the overflows/Durso pipes. The water will only drain as far as the top of the overflows unless it is designed differently AND if there are holes drilled in the *pump returns* just below regular operating water level so the pump return doesn't also siphon water into the sump, backwards through the pump.>
Is there an inherent problem with having your gravity fed overflows high on the back of the tank?
<No, unless you want to make them adjustable, in which case having a 90 degree ell (coming out of the bulkheads) and perhaps a threaded screen/pvc fitting will allow you to raise and lower them to the desired height.>
I built a sump/refugium this weekend of about 18" in height and my first baffle is 14" tall so it doesn't have a lot of room in case of power outage which led me to the back drilled idea... any comments, suggestions?
Thanks Guys! Your invaluable!
<Just remember, gravity and siphons are very reliable. Make it work for you!  Let us know if you need more assistance.  Craig>

Re: Overflow Question
I'm looking into replacing my current 180 gallon aquarium with a new one. Would like to know the differences between the standard corner in tank overflow versus using standard 2" bulkheads (x3) drilled into the back wall along the top at water level. Obviously both will serve the sump below the tank. The main thing I'm concerned with is the noise level. The corner overflow in the current tank uses a Durso stand pipe, so it's relatively
quiet already. Sincerely, Craig
<There is no real difference between the two. The bulkheads can also be enclosed in a skimmer box like the corner boxes if you wish. The noise depends on how the overflows are vented and the size of the overflows/boxes, and how far the water falls into the overflows/boxes, if used. Hope this helps you out!  Craig>

Overflow Prefilter
Greetings,
<<Hi, Don this afternoon>>
Always a pleasure to read this web-site.  It is great to see that you have some more "Pros" other than Steven helping out. yuk yuk yuk! <<uh, Thanks, I think, Oh, Pro, now I get it;)>>
I have a overflow box that has a coarse sponge pre-filter.  I typically rinse this about once a week.  It always has some decaying food and mulm attached to it.  I think that it needs to be cleaned more frequently maybe even daily.  For a lot of reasons like travel and procrastination, daily cleaning of this pre-filter won't happen.  What are my options?  The overflow feeds into the sump where I have a protein skimmer.  Should I remove the coarse pre-filter to provide more "raw" water to the protein skimmer?  <<Recommended course. See here for more http://www.wetwebmedia.com/marmechf1.htm>> Knowing that food gets caught on the pre-filter....will the protein skimmer collect the food or will the decaying food just get moved to the next coarse pre-filter just before the return pump? <<Ahh, maintenance never stops eh? You can try a micron bag on the end of the overflow into the sump to catch crud, but it too will require regular (every other day if not every day) maintenance. Maybe best to go without either and try to get to the other filter more often. >>
Also, I would like to drill the 40 gal glass tank for a 1" overflow.<<Just an observation as I don’t know what your intentions are, but maybe two holes? easier now than breaking it down, again, later>>   My understanding for this procedure if you do not want to remove everything from the tank and there is adequate space to drill the hole is:
1.  Drain the tank well below the overflow - add filtration and heat to the lowered water
2.  Clean the inside surface where the overflow box will be mounted
3.  Silicone the overflow box 8"W X 5"H X 3"D in place
4.  Drill the hole using the overflow box to catch debris on the inside of the tank
5.  Install the bulkhead in the hole ensure that the bulkhead id is at least 1"
6.  Attach plumbing to the bulkhead to the sump
7.  Ensure that the silicon is dry (6-8 hrs) <<I would wait 24 for any silicone job>>
8.  Re-fill the tank and restore heat and filtration in the sump.
Where is the best place to get the glass bit and lubricant?  <<I used water>> Is the above too risky?  I do have a 20 gal tank that would be ready in case of a serious (i.e. crack) situation.<<While the above may work and for others successfully, I  would not advise to drill anything but an empty (completely) tank. I got the first hole drilled in a 20H for a refugium and about half way through the second, BOOM, well, lets say I then waited for the glass shop to get a replacement cut for me. I got a bit locally, but there are many web sites selling them. Google search? Also, see if you have a marine society in your area, they may have some you can rent/borrow>>
Again, thanks for the help.
<< Happy glass drilling Don>>
Kinzie

Re: DIY bulkhead overflow
HI guys,
Don thanks for the support about my bulkhead overflow idea.  <<My pleasure, glad you were able to follow the ramblings of an old man>> I had thought about just placing a box around each bulkhead, but then Don made comment, and I remember Anthony touched on in his book, that an overflow the length of the back of the tank is a lot more efficient.  So...I did some measuring today to start making plans.  This is what I have so far.  I have a glass 75 gallon tank w/ 2 1.5" bulkheads about 3" from the top of tank on each end.  I want to make this out of acrylic.  The overflow about 44" across to each side, roughly 5.5" tall/high and the top lip of overflow about 3/4" or so from the top of the tank.
This is where I need a little help.  How wide/ deep should this thing be?  <<Obviously, enough to handle the elbows. 4x4 or 5x5 I would think. Unless I am missing something here>>I remember my CPR siphon overflow and even though it hung on the tank the overflow part was probably 1/2" or so wide where the water flow was.  So I was thinking between 1/2" and an 1".  This is the big question.  How to attach to the tank?  Right now I'm thinking about adding/connecting 1/4" to 1/2" edges/strips to the back of the overflow that I described above, so that now, I only have to silicone 3 edges to the tank (2 sides and the bottom)...(hope you can follow) instead of a whole big piece the length of the tank.  How does this sound?
<<Sorry Bryan, can’t say I have ever read/heard positive thoughts about using silicon to attach acrylic to glass. I would think you would be better off using glass. Or, figure a way to support the acrylic overflow with brackets>>
any suggestions/comments?  See any problems or change
anything?  Thanks Bryan <<Sorry I didn’t have better news, Don>>
P.S Craig, the elbows on my bulkheads worked.  I filled the tank like you said and everything leveled
out. sump and main.  Thanks for your help. <<Ain’t he something :)>>

Re: DIY bulkhead overflow (part III)
Don thanks for quick response about my DIY acrylic overflow for my bulkheads.  <<Glad to help>> Let me run a couple more things by you.  <Walk please, I’m an old man and can’t keep up>> I forgot to add that I 'm not going to
use the 90 degree elbows on the bulkheads with my overflow. <<OK>>  I thought that this would make it not as wide/big.  Have the bulkheads open or bare and let the flow go over the acrylic overflow and down the bulkheads to the sump.  <<Ahh, good>> (this way I can make it say 1/2" to 1" wide and won't take up a lot of room or be that noticeable.)  Does this sound fine or are there any problems you foresee? <<IMO it is better to over design than under. Last thing I want to do is tear down/redo stuff. Experimentation is good though too. Let me know how this works for you>> I was a little disappointed that people don't have luck with glass to acrylic silicone contacts, sooooo, back to the drawing board.
OK I'm at the drawing board, <<Quick Trip!>> what about this?  Add or put brackets to the overflow so that its main support is by the brackets on the tank, then use silicone around the edges of the overflow so that flow doe