I have a 65G reef tank. I had a big nitrate spike about a week and half ago where they were off the chart. Flow was bad in my tank and green algae was forming. Since I have fixed the water flow, done 3 water changes between 10-20 gallons each. The nitrates have come down some but are still present, I have fed less to the fish and the green algae is going away except now I'm getting a lot of grey dust looking build up. This seems to be a lot more on the live rock and almost seems like it is turning from dust into hair. My question is what is this dust/hair stuff?