For the last few months all of my coral has been slowly dying 1 by 1. It is mostly LPS, some casualties to now are an elegance, two torches, zoas, and a frogspawn. It has now started happening to my goni and acans. I've attached a photo of the goni. You can see it has started having some brown coating on it. Also attaching my latest icp test results from the lab. These values have been pretty stable the whole time the issue has been going on. Alk is high because of red sea pro salt, but I switched to HW-Marinemix since this test. I have two clowns, an orangespot rabbitfish, purple reef lobster, and a watchman goby / pistol shrimp aside from the coral. Any suggestions what could be killing off all my coral slowly?