Alkatronic results not consistent with Mastertronic

[CSremo]

Decided to put dKH test (Salifert) on the Mastertronic to check the Alkatronic results periodically.
Here is my first comparison. Waaaay off.
siggestions?

Alkatronic - 8.37
Mastertronic - 12.16

I’ve been using Reef Crystals. So was expecting higher alkalinity.
Recently had trouble with the calibration and had to reset the Alkatronic PH calibration with the help of customer support and that seemed to fix it. Prior to resetting I have had a consistent DKH of 4.85. After resetting it went into the 7s. Which seemed accurate at the time. But now I’m obviously questioning it again.

 

[SPR1968]

I can’t answer the specific question, but I can bump the thread to see if we can get you some help