I've got same problem as bigbird123, believed to be diatoms or dinoflagellates.

I've been fighting this stuff for an extended period (too embarassed to mention) and should have posted awhile ago. I didnt test this past weekend but the weekend before my DKH-14 and Mg-1300 (approx). How do i bring these parameters in order? I use RO water for top off and water changes...how do i control the Silicates?

I've been doing weekly water changes trying to bring my Nitrates down...still hovering at 50 to 100 (approx...yes, i know, needs to be much much lower). My UV sterilizer on the fritz...my skimmer waste collector has a drain...i have macroalgae in the sump...do not overfeed my fish to keep nitrates down.

Employee at LFS stated that my nitrate problem may be due to water change procedure; i simply drain water w/o vacuuming the substrate. Do i need to change how i change water? I been using Tropic Marin for the last 2 months of water changes and have now started using TM ProReef.

Ready for your recommendations.