Its more brown then red and only on sand bed. Started about 3 wks ago. Nitrates are .05 phosphates .03. I also feel that I have a lot of flow for my tank. I've been doing 20g water changes for past 2 months. I run marine pure plates 1 8x8x4 just added last sunday and 2 8x8x1added 2 months ago. I does nopox 1ml daily starting 2 wks ago. And run carbon here and there. Any suggestions ??