Scott's 270g aka Project Mayhem

[Scythanith]

Hello All,

I recently had a large rtn/stn event and I couldn't figure it out. It started on one coral (not new to the system and spread out from that point like a wild fire. Currently the death has stopped, seemingly confused by a large encrusted sunset montipora. But up to that point it eradicated a bunch of Acropora sp. and a M. setosa. As far as all my tests told me my numbers were all in the wheelhouse. I also use a microscope professionally and could not see any unwanted pests on the corals I removed from the system. I only observed a magnificent foxface picking at the dead skeletons once algae started to grow on them. A bit of background info:

I use all Tropic Marin products (TM Bio Actif Sea Salt, TM Bailing 3-part, TM K+ & A- Elements)
I guess that's a lie, I also dose Zeovit Pohl's Xtra
I use GHL dosers to deliver the dosing (recently re-calibrated since the death started. They were only off by 5ml/min)
RO/DI system testing 12ppm on the clean side (I know I need to change the cartridges and the DI resin is pretty spent)
I do a ~45g water change every 2 weeks
I use Hanna Alk, Ca & PO4 handheld testers
I use Red Sea Pro Test kits for Mg, NO3 & PO4

My corresponding kits test results vary quite a bit in the Ca (478ppm) and Mg (1260ppm). I performed the tests at the same time as drawing the water for the Triton vials (or at least within 10 minutes).

So Triton says I am way low on Ca (323 mg/l), high on Mg (1449 mg/l), and have dangerous levels of Boron & Molybdenum. The test mentioned Mo can cause cyano, and I do have a little patch of it in the back section of the tank. So what do you all think I should do? Where is my Boron coming from?