"Pool Math" app misleading, or city water needs "more" Borax and CYA?


Sep 7, 2018
Jersey Shore
I am not having any success in seeing any measurable (Talyor test chems) pH or CYA increases on a newly-filled pool

Being a cautious sort, I want to see a testable change in the correct direction, rather than blindly toss in what might be "too much" of any chemical
So, starting with a fill of 4545 gallons of city water into a small vinyl above-ground pool, I have reading as follows:

Added 120 lbs of salt for the SWG to reach the ~ 3K ppm required.
Had a FCL of "0", so added 3oz of trichlor granules ("Shock"), as PoolMath said that would bring me up to 4.5 FC, and the SWG was running to add at least enough to overcome sunlight consumption.

Next morning, FC 3, CC 0.5, TA 40, pH 7.2, CYA <30

Added 9.3 oz 20 mule borax with PoolMath says should give me 7.6 pH
Added 8 oz of 100% CYA stabilizer to get a claimed +15ppm CYA

Next morning, FC 2, CC 0, TA 40, pH 7.2, CYA <30

Added 4 oz more 100% CYA stabilizer
Added 3.6 oz more trichlor shock

Next morning, FC 5, CC 0 TA 40 pH 7.2, CYA < 30

I am not moving my pH or my CYA at all here - the test tube has a minimum reading of 30, and the black dot is clearly visible at 30.
pH is also just not moving, and we've had no rain, nor has water been added. There has been sufficient time (several days) for things to mix and reach a consistent level.

The SWG is clearly "working" as the little bubbles can be seen coming off the electrode plate assembly.

I had this all manageable last year, don't know what stupid rookie error I am making here.

Can I buy a vowel?


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
In some pools, CYA seems to take a long time to register. Several days or even a week.

At 40ppm TA, it’s possible your pH is going to 7.6, then back to 7.2 before the next morning. TA functions to stabilize pH.
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Sep 7, 2018
Jersey Shore
OK, so heavy on the BiCarb to get the TA up and keep the pH stable, then I'll play with the CYA.

I have been adding the CYA by dissolving it in a pail of water and then spreading it around the edge of the pool, as it seems very slow to dissolve without cushing the tiny fragments and mixing "with vigor". I can get it to form a "cloud" of whitish material that does not sink to the bottom if I am persistent. This is the Clorox-brand product, claimed to be 100% CYA.


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Follow the sock method in the future to add CYA.
Solid stabilizer is best added by placing it in a sock or nylon and hanging that sock in front of fast moving return(s). Shaking and squeezing the sock while in the pool water will help the stabilizer dissolve faster.