PoolMath Error

MasterTinkerer

Gold Supporter
Nov 28, 2016
227
Helena, AL
I think that I came across a calculation error this morning on PoolMath. It is in the PH adjustment box. Here are all of the numbers that I have in the system in the format of actual/target

Size = 20000
FC = 5/5
PH = 7.5/7.9 (raising it because I'm getting ready to add boric acid)
TA = 50/50
CH = 200/200
CYA = 35/35
Salt = 2000/2000
Borate = 0/50
Temp = 65


The box next to PH is telling me to add 29 oz by weight or 28 oz by volume of borax. But - If I put the 29 oz of borax (20 Mule Team) in the "Effects of adding chemicals" section, it tells me that the PH will raise by 0.16... not the 0.4 that I have as the differential in the PH section.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,851
Tucson, AZ
The "Effects of Adding Chemicals" section has a note written above it that states that the pH calculations are not exact. The reason being is that section needs to make assumptions about a waters TA and other levels and it does not calculate large adjustments to pH very well. The section above is more accurate.

You do not need to raise your pH. Boric acid is a weak acid and adding enough to achieve 50ppm borates rarely lowers the pH much more than 0.1 to 0.3 units. I did not raise my pH at all before adding borates and I was fine.
 

MasterTinkerer

Gold Supporter
Nov 28, 2016
227
Helena, AL
Thanks for the answer... the "Effects of adding" said that the ~50# of boric acid would lower pH by 0.3, guess I'm gonna find out :)


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MasterTinkerer

Gold Supporter
Nov 28, 2016
227
Helena, AL
I put a 4 lb box of borax in the pool - favoring the bottom number on the calculator page over the top number... then added 50# of boric acid... the end result was a pH of 7.5, so I guess it turned out OK