[Blakes Living Reef.ca]

You have a cyno bacteria which will take over your tank and may harm your corals. Your live rock and sand(?) are more than likely saturated with phosphates. You need to remove all of your live rock/sand and place them in a covered, heated tube for a period of 3-4 weeks (or more) with a small skimmer or water changes (every 2-3 days). This will allow your rock/sand to re-cure. Clean your rock first (toothbrush works great) and re-clean at each water change. Only place back into your main tank when water stays clean, rock smells and looks right. This sounds drastic but just adding chemicals is wrong! You have to find the source of the phosphates and eliminate them (overfeeding/overstocking). I have found adding a Phosphate Reactor to the system along with good Reverse Osmosis water will prevent further issues.