Although all stressors count, as ususal, I'd guess
less toward the alkalinity and
more toward light shock or lack of water flow.
The lack of nitrates will exacerbate both of those sensitivities.
Feed Him
Best best is some liquid food....a nitrate supplement and/or amino acids. Do not do a huge dose if you choose to start either one, but start with very small but regular doses.
Potassium nitrate (Spectracide stump remover) dosing steps can get you started with a DIY formula for NO3, including calculators to get your doses correct. If you use something else, please post what you choose....or at least make sure you start with a very conservative dose.
diy amino acid should have some good info on the amino acid side. Conservatism should dictate your dose here as well.....in particular because there's no test kit for amino's to let you know when you've gone too far.
Fix The Lighting
Correct the light situation (if necessary) by finding out what the light is like where the coral came from.
If it came from the LFS, take a light meter and measure their lights, or ask them to measure for you if they have a light meter of any kind. Let us know what happens here. Converting from PAR to lux is no problem.
You can use a free lux meter app that uses your smartphone's camera....get one and test it out first. Sometimes the apps aren't compatible with specific cameras so you may have to try more than one. Post results and we can help get you started. FYI, a full-blast sunny day should approach 100,000 lux. Overcast would be around 10,000 lux.
Fix The Flow
Do you have any idea what the flow was like where he was growing?
Can you post a full tank shot that include the current flow pumps?
