Chaetomorpha 12/15/06
I have two different types of Chaetomorpha growing in my 29-gallon refugium:
1.  The first type is the typical "spaghetti algae" pictured on most websites.  It is very curly, and not too dense, much like a Brillo pad for cleaning dishes.  The individual strands are quite thick, and it grows in a ball which sits low in the water (barely any of it floats above the water, and if you take it out of water, it collapses and lays flat).
2. The other type is very dense and the strands are much finer & straighter.  It grows in a floating mat, maybe 2.5" thick.  This type floats higher in the water, and some of it grows straight up like grass.
New growth projects straight out of the mat in all directions, about 1/2" long.  The new growth on the top side of the mat is out of the water, and looks like grass.  If you take it one out of water, it retains it's shape.  The LFS where I got it tells me this Chaeto grows just as well in freshwater as saltwater.  They have it growing in both types of water at the store, and have switched it back and forth with good results.
Is the second type really Chaetomorpha?  I can't find any pictures on the web that look like it.
<Your second type may be Cladophora, can't say for sure without a pic.
It may also be Gracilaria, again, need a pic.>
Is it okay to have both growing in the same refugium, or will they compete with each other resulting in reduced growth?  Should I get rid of the second type?
<Chaeto does thrive on nitrogen and phosphorous and if the food supply dwindles, so will the Chaeto. Having the two types together should pose no problems. It is best to thin out on a regular basis.
If the outer edges begin turning brown, it is a sign that the needed nutrients are absent or your lighting is insufficient for growth.>
Thank you,
<You're welcome.  James (Salty Dog)>
Steve in Denver