Driftwood Moss (blackish in color)

[MrSickLid]

I purchased a large piece of driftwood a while back. Suddenly out of nowhere there was a blackish mossy like substance growing on it. I just recently moved and had the piece sitting outside to dry and left it there for about three weeks. I then washed it with a brush and extreme hot water in hopes to have this disappear. But when I put the piece back in the water, not only did I have an issue of the piece not wanting to sink but I also noticed the blackish mossy like substance was still present.

My questions are. Has anyone else had this occur? Is it good or bad? What is it? Most importantly will this harm my fish?

Your help is much appreciated.

[blaciarmd]

It is common on driftwood, but I have never seen it grow too much out of control. I had some grow on my driftwood. I am not an expert, but it is algae not a moss. No algae eating fish will eat this though. Certain Spectrums of light might encourage the growth of this type of algae. Is your tank close to a source of natural light?

[AndrewBl]

This is black brush algae. It is caused by, among other things, an abundance of certain forms of iron in your water. The easiest way to get rid of it is to dose with Excel (made by Seachem) in the dosage recommended on the bottle for a few weeks. There are a few creatures that eat it but it's much less reliable.

[dstuer1950]

Does it look like this?
http://i70.photobucket.com/albums/i97/dstuer/003-4.jpg
This kind does not feel slimy, it feels fibrous.
This would be a form of caulerpa, and since it stays mostly on the log, it doesn't bother me. And the fish tend to pick on it, there are young Gymnogeophagus, a live bearer of the genus Xenotoca, and a few small bristle nose plecos.
If you let wood dry, it will become buoyant. You can soak the wood in a bleach solution over night to remove the algae, but then you must soak it much longer in a solution of water and sodium thiosulfate to remove the chlorine. A chlorine test kit would be advised to be sure the bleach has been removed
I just let the algae grow, and let the fish graze on it. I believe adding http://i70.photobucket.com/albums/i97/dstuer/013.jpgplants that compete with the algae help to keep it in check.

http://i70.photobucket.com/albums/i97/dstuer/008.jpg