Dosing help? Low alk, good calcium, high magnesium

My 20Long lps dominated nano has been going through lots of swings and changes with cal alk and ph. I started using kent probuffer dkh to fix ph problem and to hopefully raise alk. My ph is stable now at 8.3 during day, and im assuming what is 8.1 at night (hard to tell with api). I brought alk up from 6.5 to around 8.5-9 using the buffer. Today my levels are 430 cal, 6.3 dkh, 1500 magnesium. I do have around 35 small frags in the tank, could this be sucking up alk like crazy? I really never had a calcium problem, just alk goes nuts on me. Possible causes? Or is this normal for my stocking size. All frags are very tiny. I run 3x dt volume rated skimmer and chemi pure elite, phosban (temporarily for cyano), poly filter pad, and purigen, 20grams of matrix carbon also, all in sump.

I have brightwell 2 part a and b. It says to dose equal parts. Does this mean i can't use it to fix my alk problem alone? Will it skyrocket my calcium if dosed equally?