I have had my 150gallon running for about 6 months so far. I currently only have a lionfish, a couple of sea urchins and a mexican snail. I am having problems cleaning my sand. It seems to have this brownish colour on top and nearing the bottom it turns to an almost yellowish colour. My water quality checks out ok and I even have baby feather dusters starting to grow on my rocks and glass
I do weekly 40-50% water changes using RO
water. I am not sure if the brownish colour is from lack of flow or from cleaning my sand too lightly.
Any tips would be great. Thank you.