I forgot to add, I do a 20% water change every week and use both Purigen and Chemipure Elite. I hasn't been six months yet, but I could change those if you think it would work. The bag of Purigen isn't pure white like it was when I first put it in there. It has some brown and black patches. I tested for phosphates and have a reading of 0, and nitrates are at 0 as well. Temperature has been the same 79-80 degrees. Should I turn off the lights for several days or a week? Right now it's a FOWLR. Aside from taking out the red stuff with a turkey baster, what else can I do?