DKoKoMan's 150g Reef Tank

[DKoKoMan]

Ok so yesterday I did water tests for Alk / Cal / Mag / PO4. I had received my new Hanna Alk and PO4 checkers. I also received a Salifert Calcium test kit. The following results came back:

ALK: 12dKH (Hanna)
CAL: 500ppm (Salifert)
MAG: 1350ppm (Red Sea)
PO4: 0.16ppm (Hanna)

I had been previously using the Red Sea Reef Test kits which indicated the following:

ALK: 11.5dKH
CAL: 460ppm
MAG: 1380ppm

PO4: 0.25ppm (API)

My doser is set to deliver 15ml - ALK (twice a day), 15ml - CAL (twice a day) a total of 30ml each. I have a bunch of frags, LPS, clam etc. So I didn't think I was dosing too much. I have since reduced my dosing to a total of 10ml of both ALK and CAL delivered twice. Hopefully the levels drop a bit as this is way higher the. I expected.

My ideal parameters are:

ALK: 8.5-9dKH
CAL: 420-450ppm
MAG: 1350ppm

PO4: 0.03ppm or slightly higher.

I am currently using IO - Reef Crystals and have been at the beginning of my 75g. Is it unrealistic to get the ALK / CAL levels down with this salt? Any recommendations on moving forward. I feel like these new parameters are pushing the high end of the limits, although my sps haven't had any STN or RTN. I don't want to have large fluctuations in water parameters.

I currently do biweekly water changes (30g which is about 25%). Even without dosing anything I think the RC will push me outside my desired parameters. Looking forward to some responses from the seasoned reefers here on Canreef.

Thanks!