blue acro bleaching

I am seeing what I believe to be the first casualty from my recent stay out of state, when I left the care of my tank to my family. Although it's pretty automated when I leave, something changed. I did my usual 15g WC, it was ten days after last WC, when I got home Thurs. 7/2, params on 7/3, temp. 78, SG 1.025, pH 8.3, alk. 9dkh, phos., ammon., nitrite; 0, nitrate 10ppm, calcium a bit up, 460. That's the usual chemistry and param level. Nothing new or changed but I noticed a rapid progressive bleaching on the tips of my Joe the Coral, blue acropora sp. started after lights out last night 7/4. I'm not quite sure what's causing it or what obviously must have changed that I haven't figured out yet. Anyone with ideas or thoughts? Thanks, Ann Marie Also, tank is over three years old, open brain, frogspawn, green button polyp corals, clownfish, sailfin, sixline wrasse, skunk and peppermints, CUC snails, blue legs, emeralds, de-nitrate in sock, TLF phos. reactor, protein skimmer, 120lb LR, 2 1/2" SB, chaeto, mangroves in fuge 48" sunpod 2 150w 14k MH

 

Is it bleaching or suffering from RTN? Are the polyps still there or not? It could be caused by a shift in the temperature.

 

The polyps are still there, I'm not sure if temp. did any swinging when I was gone, although my family didn't think so. There's a fan on tank during light hours and a heater and it's been consistent so far, but I have no idea what the house temp and whatnot may have been when I wasn't there, so that may be a possible cause. I'll keep working on it. It's my favorite coral and was thriving and growing until now

 

Everything looks good to me. Have you checked your magensium, and doublechecked all your parameters? Make sure you check against a calibrated refractometer, check with another thermometer, use a different test kit or LFS.

How much flow do you have in the tank, and how long have you had the acro? Is it the only acro in the tank, are any others doing OK?

Also, check the coral for red bugs/acro eating flatworms.

Not saying its any of these things just some things to make sure.
Sometimes mysteries happen but a lot of times it's something simple like a test kit expiring.

 

Any recent additions to the tank that may have introduced flatworms?
Also, start running some carbon as a preventative measure just in case of some sort of chemical/toxic introduction that may have occured while you were gone.