green hairy mushroom bleaching

I've had my green hairy mushrooms for about 2 months - until now, they were the healthiest-looking corals in my tank. They are about mid-way up, with mild flow. I don't target feed them, but I do add live plankton to the tank once per week, which should feed most of the corals/filter feeders.

Yesterday I noticed that their color was much lighter green, with areas almost white-ish. I can only assume they are bleaching for some reason. Water parameters are all normal - temp 77-81 degrees, ammonia/nitrites 0, nitrates undetectable, phosphates around 0.2, calcium was at 380, SG 1.025.

The only thing I did differently was that lately I started adding some Seachem Reef Complete - which is calcium, magnesium and strontium in their proper ratio (so they advertise). I had dosed with some yesterday. So I wonder, could that be the cause? All the other corals are doing fine, as are all my other inverts (and my copepod infestation). Any suggestions?

 

Are you testing for what you are adding. The recomendations on the bottles is always a general amount. To truly get your reef levels right u need to test for everything you add.

 

I test for calcium, but I don't have a magnesium test yet. I have been dosing based on my calcium levels. I assumed (correctly or not) that as calcium is depleted, so is magnesium.

 

Bump. Any ideas?