Unhappy Corals

[mikellini]

Hair algae can bother corals, both by touching them and by releasing chemicals into the water. My first thought was that your water is too clean. I would get the hair algae under control first and then decide what to do next. Using a phosphate binder and snails, along with manual removal, usually works quite well. If it's particularly resistant, try starting with a couple of days of lights out.

The chaeto will not out-compete hair algae for nutrients, so I'd remove that off the bat. Then run separate carbon and GFO or Phosguard, using the full recommended amount for your water volume. Add 2-3 turbo snails, continually place them on the hair algae so they keep eating it, and manually remove what you can. Continue to feed your tank/fish well to ensure trace amounts of phosphate and nitrate are available for corals. Once the hair algae is gone, test for nitrates and shoot for somewhere around 2-4ppm. Easiest way to achieve this is to feed more. Hope this helps.