I took it for hair algae, but it has very thick strands. Pain in the *** to get under control. I started my tank with sterile rock, had a ha outbreak like this, and then almost had it wiped out. Then I added a fuge and about 60-100 lbs of more dead rock. Then the algae made a comback. I am currently using a ton of gfo and exporting by hand. I just wish it would all die off