I believe my crash a couple of years ago was caused by chloramines and my water too, granted my filters were getting depleted prematurely and I wasn’t aware of the issue. Same thing happened: things began looking grey and then widespread death. It was over a matter of a few short weeks. I now change my pre filters every four months just in case.
Good luck and I hope you figure out what’s wrong, but I’d suspect something in the water too.
Good luck and I hope you figure out what’s wrong, but I’d suspect something in the water too.