corals bleaching

I am having a problem I hope the experts here can help me with.

Last week I noticed some of my corals starting to bleach. My green hairy mushroom is a much lighter green now (almost white-ish in some spots), as are my flower corals. My zoas also are not opening well.

However, to contrast, all my LPS and SPS are doing great.

My readings: Temp 78-81, SG 1.025, Ammonia/nitrite 0, nitrate undetectable, phosphate 0.2, calcium 380, alkalinity 6 mEq/L.

Any ideas as to the cause and how to correct?

 

Don't know what the problem is but if your alkalinity is 6 meq/L, that is too high IMHO. That is equal to 16.8 dKH. What is your Ph?

Jack

 

pH is 8.2-8.4

 

Are you feeding anything for filterfeeders..??
Running charcoal..?? You use anything for trace elements, or alot of Waterchanges.??

I run the same light set-up on a custom 60 gal.. So lights should be OK..
Did you do any bulb changes..? Are your bulbs getting old..?

Good Luck, Larry

 

I run carbon and phoslock in separate phosban reactors. But haven't changed the media in about 2 months - getting a bit old.

I feed the big corals mysis shrimp, and I add live phytoplankton to the tank once or twice a week.