I have the same kind of thing... I think its cause my diatoms went away, and my nitrites finally went down... So, low I have tons of green algae everywhere, and also some red algae that looks like puffs... Its bulky looking... What should I do, clean it or leave and get some kind of snail to do it... Cause I have a picaso trigger... Right now I use tap water, and its not close to a window either... Any other suggestions??? On what it is??? And how to get rid of it???