Your TDS should be zero. That is probably what is fueling your algae bloom. Your nutrients are low and your ALK being at 11+ and then fluctuating is most likely why your SPS is dying. Low nutrients normally has alk around 6-8 dkh. You should be testing your ALK everyday at the same time of day until you get your dosing dialed in. You can't be testing ALK once a week when you're trying to get your dosing correct. You should check the output of your RODI water and make sure the TDS is zero to rule out a TDS bump in your holding bin due to the pump transfer as you stated.
Correct your TDS, get your dosing dialed in and keep the ALK stable throughout the day/week and your corals will turn around.
EDIT: I'd also lose the glass top and make a mesh screen to keep fish in. Buy a window screen frame kit of Amazon and the clear mesh from BRS and you got yourself a top to keep fish in without hindering your lights. It will also help with gas exchange.
Thanks. I’ll order the mesh kit ASAP and testing daily for the dosing, I put to much trust in the sea chem label. Bad choice. Hopefully I can get the correct amount to get the alk at the right number.
So with my nitrates being between 5-10 I should be holding the alk at a steady number between 6-9? Just want to be sure that’s the right combination. Thanks.