The 85F degree thing could be it. Listen Max (it would really help if I could remember your first name longer than 24 hours!), SPS can be tolerant of our errors, but at one point they've simply had enough. I've boosted my pH from 8.0 to 8.75 in about 3 minutes flat being an idiot, and all my SPS slimed horrifically, but within an hour the numbers lowered again and the corals were fine. I sat in front of the tank that day for two hours not having a clue what I could do to fix the problem (um... adding some white vinegar was an option).
I've had my tank go up to 85.5F but cooled the tank down again.
Once I set the a/c unit to dehumidfy and forgot, the tank went from 83F to 76.7F and my slimer sloughed off its tissue. I snatched it from the tank, fragged the heck out of it, mounted it on a new rock, and put it in my son's 81F tank and it survived. Later than day when the main tank was back up to 81 like normal, I moved it back.
Corals touching other corals can cause losses, either in part or 100%.
The key is stability. That's it. If you can do that, you'll keep lots of healthy livestock. Extremes are the problem. Your tank runs a little hotter than the typical real reefs.
Since I switched pumps and replaced my skimmer, my tank is now at 79 to 80.5F around the clock. I would prefer to keep the tank around 81F, but that isn't an option unless I have the heaters on all the time. And that seems dumb. I'm not running any fans at all, only keeping the fish room at 78F, and that is actually not cool enough to avoid condensation (particularly at night). I'm going to have to research dehumidifiers again, it seems.
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It cost about $40 US. It is a 110 - 120 Volt unit that uses about 45 watts. I have no idea who would use this in their computer!
