Faded blue corals

[nashlake]

All of my blue corals are light tan with blue tips. I had been using zeovit to bring down the phosphate level in the tank for about 18 months but never had any real success with the method and stopped using it about 2 months ago.

I went back to using GFO and the phosphate level is now down to .03 from .07
The alkalinity is at 8.5, CA is at 400 and Mag is at 1400. I am using Tropic Marin Pro and do a water change every two weeks.

Any suggestions would be greatly appreciated.

 

[mordibv]

Add lugols or potassium ..Since it's a test we don't usually use .Levels are unknown .Add carefully