pH Not Moving - thoughts?

[GregoryRG]

I'm puzzled that my pH didn't go up when I added borax per the pool math calc. Here are the numbers I used for the calculation prior to adding the borax in the amount calculated yesterday evening:

1. pH (current): 7.2 to 7.3 (darker than 7.2 but lighter than 7.5 on the color meter in the TF100 kit)
2. pH (goal): 7.6
3. TA: 60
4. Borate: 15-ish (going by the test strip kit)

So, pool math says that to go from 7.3 to 7.6, add 12oz (by volume) of borax. My TA is low, so I figured it wouldn't hurt until I can build my aerator.

I added 12oz, waited about 90 minutes, pH stayed where it was. Of note is that I added 16 oz of HTH Metal Control at the same time and filled a knee-high stocking with 7oz (by volume) of CYA to get my CYA from 60 to 70.


Any idea why the pH would not have moved? I just ran all my numbers this afternoon:

pH 7.2
FC 6.5 (getting ready to run the filter 24/7 with the eyeball output breaking the surface for some aeration while I build my aerator)
CC 0.5 or less
TA 60 to 70
CH 125
CYA 60
Borates 15 to 20? Hard to tell on the LaMotte test strips (ordered boric acid for borate push).

Thanks,

Bob

 

[PAGirl]

I believe I read that CYA is a bit acidic, so it might counteract the Borax addition. I think it's best to not add a lot of things at once so you can monitor each result individually.

 

[duraleigh]

pH calcs in pool math are not perfect.....there's too many variables. Simply test again to prove to yourself your pH did not move and then try the same thing again. You might even try 1/2 the suggested amount if you want to sneak up on it.

From PoolMath (bottom of the page)

Note: pH calculations are not exact. These numbers are only suggestive of the relative magnitude of the pH change you can expect. Small changes, +-0.4, with pH between 7.2-7.8, TA around 80-120, and Borate near zero will be approximately correct. The further you go from those ranges the less these pH changes will correspond to reality.

pH of 7.3 is also fine, btw, but if you want 7.6, that should do it.

 

[GregoryRG]

Thanks, Dave. I should have read the notes and cautions better!