Calcium levels at 320ppm

[GSPreef]

I am new to saltwater aquariums and have been trying to get my calcium levels up since I want to create a soft coral nano tank only. My tank is 15 gal and it has been at 320ppm for the past months. I keep changing testing kits and still 320ppm. I am currently using fritz premixed saltwater from my lfs, I keep the salt at 35ppm. I am dosing all for reef 3ml with a dosing pump. should I increase my dosing amount? TYIA

 

[Tahoe61]

Definitely don't keep dosing.
What testing methods specifically, as in brand of test kit, method?
A newer 15 gallon tank shouldn't require dosing.
Alkalinity and Magnesium values?