Is it possible that my weekly water changes are causing my brown algae problems? My 55 FOWLR still gets brown slime in it, and I'm thinking it's due to the water changes. I just use dechlorinated tap water for changes, and instant ocean salt. The corraline in there just barely hangs on for life, the fish are fine, the nitrates are about 20ppm. I keep seeing people talk about RO water only, I don't have one of those. Should that be my next purchase? Thanks everyone.