Hi - something weird seems to have happened to my tank since I added the hornwort. There's all this greyish-greenish brown stuff gathering on the bottom. Since the vet thinks Poly's sleeping area should be kept as clean as possible to prevent reinfection, I'm not entirely happy with this - also since it's coating the anubias leaves. Is this dead algae? If so, is it likely to be a problem? I've never seen anything quite like it - when I tried to clean it out today, it was fluffy and tended to fall into tiny particles, almost like dust! (It's not dust). Water chemistry was okay. I have some green (dot) algae growing on the glass now (think Pol will like that; the snails do - they have come out again), and the hornwort is also growing, but has lost all its lower leaves - is this stuff also possibly decaying hornwort leaves? Or some combination of plant matter? Pol's been out of the tank (at the vet's ) for a week, so I know it's not any sort of goldfish dirt!
BTW, exact numbers: ammonia - 0. Nitrite - 0. Nitrate - 10. pH - about 8.2. Temp between 76 and 78.