Hugo, I did test everything and thought it was alk burn and such. I changed salt from DD to TM and nothing. Everyhting you are describing is exactly what I was dealing with. Yes, my caps were one of the 1st things to go. I'm not sure if there is a test for chloramines and if never sent a sample to get tested. I do know that after upgrading my rodi filters to the chloramine removal and doing many water changes things got better. Not overnight, but slowly. After about 3 months and miltiple monthly water changes I'm able to grow sps,lps again.
I know if would be nice if I have a test showing that it truely was chloramines, but I think the upgraded filter fixed the problem.
Jeff