Acan Suddenly Bleaching

[dcmartinpc]

I have had a rainbow acan in my tank for several months with 0 issues.

I have been dosing Kent Tech M Magnesium to help with a Bryopsis problem I have.... I have also been dosing Microbacter7 as a bacteria source and Bioptim as a carbon source. I have been doing both of those for 2 months now.

2 days ago I came home and my Rainbow wasn't fully expanded. Last night I checked on it and it is starting to bleach. I have about 10 other acans that are all fine.

I did a 15 gallon waterchange last night, and I am going to do another one tonight.

Phosphate: 0
Nitrate: 0
Nitrite: 0
Ammonia: 0
Calcium: 450 ppm
pH: 7.9 - 8.1
Salinity: 1.026
dkh:8
Magnesium: 1800 ppm

I know my magnesium is elevated, but I have dosed it before with no problems.

The only other thing I have added to the system is a couple peppermint shrimp, which I JUST found out last night can sometimes pick at acans...

Any ideas/suggestions. If I need to pull the corals and rock out to get the peppermint shrimp, I can, so that is an option.

Don

[firsthesitation]

It would appear your Alkalinity is low too, usually I like to keep mine closer to 10. You're on the right track with the water changes. Anything else you added or changed recently? Bulbs, fish, clean up crew?

[dcmartinpc]

I changed bulbs a couple months ago. I switched out to the new Icecap T5 bulbs. They were all looking marvelous, then suddenly this.... From what I know, and I may be wrong, when running ULNS, which I am, it is recommended to keep the Alk at that level. Ocean levels of Alk are actually 7-8 if I remember correctly.

Please, keep the ideas coming

Don

[ckusnierek]

Parasites?
Have you touched it recently?
I know I have touched corals and did not realize I had soap or somthing on my hand and had the coral upset for a while...

[Blurple90]

Keep an eye on those shrimp but hopefully the water changes will solve your problem.