Budget doesn't exist in this hobby: Brian's 45g Build

[Etaloche]

I thought by now I'd be able to figure out the balance in my tank, but I'm still struggling. SPS are thriving, but I still struggle to keep LPS alive. I have a clam and a sea apple which show no sign of stress so it's not the water quality. I've pretty much never had luck with Euphyllia, now my acan and plate coral are deteriorating out of nowhere. I've tried feeding them as well which usually recovers LPS very quick in my experience, but no luck this time. Don't have a test kit to test nitrate and phos, but rest of my parameters are as follows. Can anyone give me some suggestions/advice on what I could do to achieve a balance between LPS and SPS

Alk: 9.6
Calc: 450
Mag: 1360