Tank fungus

Question
I have a 55 gallon tank that I set up just after Christmas, so I have had it approximately a month.  I am not new to fish tanks, because I did(and still do) have a 10 gallon tank as well.  I have noticed some wierd looking stuff that is in my bigger tank that I have never seen
before.  It looks like some type of fungus, I guess, that has hairy looking stuff around it.  There are large and small pieces of this stuff. (It is like a light tan color and it is on the rocks) I tried to get as much of it out as I could and I done about a 20 percent water change as well.  But I am sure I did not get it all out.  What
should I do?  What caused this?  Can I kill it?  I don't want my fish to die.  Please help!!


Answer
Hi Michelle
I would say that sounds like diatoms.  Kind of like an algae, but it's not an algae.  It's also common in newly set up tanks-most likely they show up after the tank is cycled.  I'm not real familiar with this algae, I know it has something to do with nitrates and/or silicas in the water that helps them survive.  I know oto cats like to eat diatoms, if you don't have large fish a few of those wouldn't hurt.  But I think you still need to check into a few other things listed below.  Here's a link with pictures:

http://saltaquarium.about.com/cs/algaecontrol/l/blpicalgaediato.htm

Like I said, I'm not real familiar with these.  I did find a link to explain a little more about them.  For treatment, I'd suggest to be sure to do weekly water changes of about 25-30%, this will help keep the nitrates down in the tank.  Nitrates should stay under 20 ppm. And do the water changes every week, not just for the treatment.    

http://saltaquarium.about.com/cs/algaecontrol/a/aa091100.htm

That last article seem really good and informative about them.  Be sure to read the second page as well.  It seems to be geared towards a saltwater tank, but I know freshwater tanks suffer from it as well.  Also it says on the article about CO2 levels, maybe consider adding another filter on the tank if you only have one.  The water agitation will help promote gas exchange, and extra filtration won't hurt.  

I hope those articles can help you, I learned a lot reading about it lol !!  Let me know if you need more help!!

Christy