So I added 16 boxes of 20 Mule Team Borax to my water about 3 weeks ago, and tested about a week later using Lamotte strips. The original reading was dead-on 50 ppm.
Last week, I went through my weekly battery of water tests, and the test strip read very slightly darker than 80ppm. (I was guessing maybe 65ppm)
Yesterday, I tested again, and it read slightly lighter than 80 ppm. (I was aghast at maybe 90ppm)
I have not added anymore Borax or Boric acid to the pool at all since my initial dosing. I've only had to lower pH so far, and never had to raise it yet.
Can anyone guess what might be going on here?
Yesterday's test results:
FC - 5
CC - 0
TC - 5
TA - 100
pH - 7.5
CH - 250
CYA - 40
Salt - 2200
Bor - 90??