Thanks very much for the suggestions; as I mentioned I've had my water tested and gotten fish from multiple sources, plus I'm using a probe salinity check through my Apex, as well. The tests are always consistent numbers across the board. Still debating getting some Hanna testers, though. It'd be a nice upgrade.
Any particular reason for the carbon and GFO? I don't have a Phosphate problem.
I do have a fuge - no macro at the moment, but that's where all the nuisance algae hangs out. I scrub and scrape it every couple weeks, and plan to get macro soon. My understanding was also that 10-20 nitrate was a good place to be, as well. Any particular reason to shoot lower?
Stray voltage is an interesting possibility for sure. I'll see if I can find any shorts or frayed wiring.
Thanks very much again, I really appreciate it.
Sorry about the mean Hippo, that's rough

. The only reason I'm more fully eliminating aggression is that some new ones have literally died while inside the box, and my other fish stay away from it, not to mention never seeing it when I'm home, though that's less relevant.
Regarding the tests, yes, the stores I've gone to both use API, but I gave them each $5 to run their high grade tests as well (Red Sea, if memory serves), and got the same results. I'm hoping an ICP isn't needed, but will do if it comes to that.
Temp is stable and controlled via Apex with redundancy in heater. ~1 degree swing through the day.
pH is stable and holds around 8.1-8.2, again with relatively minor swings of ~0.2 . I have a small amount of Kalkwasser in my RO, and dose two part.
I've been using Instant Ocean Reef for about a year now and have my own RO system. I do a change weekly (5 gal) and test the new water before adding it.
Thanks very much - as you know it's unbelievably frustrating to go through this. The fact that I have fish that have been around for > 1 year is a success in my mind, and just makes me think there's something else going on that I'm not seeing, so it's aggravating.