Big tank has some issues as you will see. It's not just lighting spectrum difference in photos.
April:
June:
April:
June:
Bad coral bleaching. Hair algae. Bit of caulerpa, which I did not know was in my system. When school got out and I was able to breathe, I saw that I had changed multiple factors and did not spend the time monitoring, thinking through, and responding to problems that the tank needed.
Mid-March I removed a gigantic Echinophyllia Hollywood Stunner. I forget when, maybe May, I noticed a cloudy area in the sump return section which turned out to be a large concentration of precipitated 2-part. I responded by cleaning sump, assuming it was because the Echino had been sucking up most of the additions and reduced dosing by about half. Meant to test frequently but did not.
Sometime around then I had decided to redo my in-sump refugium that was basically live rock, weak chaeto, and weird algae blobs. Took one of the live rocks out to seed new 20g tank and removed all algae and was going to change light, only I never got around to it so it is basically not a fuge (no light). And I have no fish in the DT to eat algae. I was thinking it was phosphates or something in my RO/SW but the other tanks only had algae growing on powerheads even though they got more food. Too many student hands working in the tank and disrupting too much. Hadn't been feeding tank much, thought maybe corals, nem, and shrimp needed more food, so starting feeding more. Wasn't paying attention to sandbed or water changes to deal with algae cause.
I had been wondering why some small acros I had were staying brownish since the fall, borrowed PAR meter and got a lot of measurements and got confused after trying to quickly figure out through internet searches how much light I "should" have, read that others with my same tank or corals had way more light than me, cleaned the Kessils, and then thought I would increase intensity. I thought it was gradual but could it have been too much light? Don't think so. In late May I realized maybe that was a bad idea and started reducing intensity. Now it might be too low.
__Fast forward to now. Gave tank a good cleaning after a few weeks of none: scraped walls, soaked (briefly) powerheads, pulled algae, removed and scrubbed a rock or two, removed some sand detritus, cleaned detritus from sump, did water change, tested water, really looked at it. Feel better about it now and ready to deal with it and get it back to good health but not sure what to do.
Testing - started with the basics and tested everything just to have the info:
Salinity: was 38-39ppt! now 37 (normally it is ~36, thought Apex was wrong because all other tanks' salinity is fine at 35. I was following the recent post about 2-part raising salinity, so seems like that's not it unless my additions are unbalanced)
Temp: 78-80deg (77-78 in Apr/May)
pH (Apex + API): 8.3 PM - 8.45 AM (Dose Alk at night when no students are raising CO2. Since I started that, no changes between school and non-school days. There were a couple dips to 8.15 in Apr/May)
dKH/Alkalinity (Hanna): 9.1 couple days after water change. Been ~8.4
Calcium (Red Sea): 425
Magnesium (Red Sea): 1440
Nitrate (API): 0
Phosphate (Hanna): 0 (could be there but not measured or is taken up by algae)
Why the coral bleaching? What should I try to fix this?
All the tissue is there. In the photos of the war coral and cyphastrea you can see that the areas that were shaded from the light have more color than the surfaces in full light, which is why I suspect light problem. Acro has good PE, but maybe that's about feeding, not light.
Feed more? If I feed OysterFeast, everybody puts out feeder tentacles. LPS accept meaty bits. Have been feeding infrequently.