I've got this algae growing on my sand bed and a bit on the rocks. i thought it was GHA but nothing will eat it. I know it isn't GHA because I put some in on a frag plug and my hermit crabs ate it immediately but nothing I have will even touch this. I have bought MANY things thinking it was GHA because it looks exactly like it! does anyone know what it is? i want it gone but if I don't know what type of algae it is I cant get rid of it easily. I have been doing water changes weekly and my nitrates and phosphates are at 0. i also use RODI water so i really can't figure out what I'm doing wrong.