Nitrates 0 Phosphates 0 New Bulbs Good flow New power ehad in sump with my chaeto Use RO DI water Running chemi pure elite and GFO I do about 3 water changes per month Why do I still keep getting annoying patches of cyano, especially in my sump\fuge? It grows on top of my chaeto. I know, you might say that the slime is eating the nitrates\phosphates before the test can get them. But then why when I clean the slime out of everywhere I see it, and then test the water over the next few days, my tests still come out good? But then a week later the cyano starts forming again. Are some strains just that hard to get rid of? Should I use red slime remover? It's not like it's epidemic, you really have to look at it to notice it, but it's annoying for me, and I can immagine that if I let maintenance slip up, this stuff would take over rapidly.