CYA above 50 affects alkalinity - question

[JoeN64]

Once a month I take a water sample to Leslie's to keep my pool warranty if effect. Today I noticed that the Leslie's test had my TA at 49 when I tested it at 70 just before going. They also tested my Ph at 7.9 when I tested at 7.6. I asked about the differences and he explained that there is a formula that must be used when CYA is above 50. TA - (CYA/3). I use the Pool Math app and entered my TA at 70 and CYA at 78 and there was no recommendation to add baking soda. Does the Pool Math app not take high CYA into consideration or utilize the formula? Should I be entering the TA result from my Taylor kit, or should I do the conversion before entering the number into the Pool Math app? I know that it would be better to get my CYA below 50, which I will work on, but I want to make sure my TA isn't too low. TIA.

 

[PoolStored]

TLR
Ignore the pool store results. Use your own test results. Any adjustments needed when it comes to calculating chemical additions is handled by Poolmath.

Long version:
There are 2 values for TA. For example a TA of 100 and a CYA of 90 creates an adjusted TA (called carbonate alkalinity) of 70. Basically the math is substract 1/3 of CYA value from the TA so 100-(90/3)= 100-30 = 70.

Pool math makes the adjustment.

In more technical terms from Taylor Technologies manual:
Therefore, the total alkalinity titration measures both carbonate and cyanurate alkalinities. This affects water balance calculations because the alkalinity term in the Saturation Index equation is strictly carbonate alkalinity.

^^this said another way, just manage your pH and keep it in the 7s. If you need to adjust TA because you are using CSI to avoid scale, feel free.

 

[JoeN64]

TLR
Ignore the pool store results. Use your own test results. Any adjustments needed when it comes to calculating chemical additions is handled by Poolmath.

Long version:
There are 2 values for TA. For example a TA of 100 and a CYA of 90 creates an adjusted TA (called carbonate alkalinity) of 70. Basically the math is substract 1/3 of CYA value from the TA so 100-(90/3)= 100-30 = 70.

Pool math makes the adjustment.

In more technical terms from Taylor Technologies manual:
Therefore, the total alkalinity titration measures both carbonate and cyanurate alkalinities. This affects water balance calculations because the alkalinity term in the Saturation Index equation is strictly carbonate alkalinity.

^^this said another way, just manage your pH and keep it in the 7s. If you need to adjust TA because you are using CSI to avoid scale, feel free.

Thank you for the quick and detailed reply . I had assumed that Pool Math made the adjustments, but I got concerned when I saw such a big difference in the test results.

I guess it would be best to stop using the tablets for a while and stick with liquid chlorine so the CYA will dissipate over time with evaporation and refills and rain.

 

[duraleigh]

CYA will SLOWLY degrade but evaporation has no affect. rain will help but not as much as you think. You are close to what we suggest as Max CYA......ditch the pucks!