TA level - TF100 vs PoolMath recommendation?

[mberlew]

Hi all, just ran my test kit (TF-100) and got following results:
FC - 4.5
CC - same
PH - 8.0
TA - 80
CH - 325
CYA - 40
The instructions in the TF-100 say the recommended level for manually chlorinated pools is 100-120. But PoolMath is telling me ideal level is 60-80. That's a pretty big difference unless I'm misinterpreting the TF-100 instructions.
I assume I should trust PoolMath? Thanks in advance for any advice!

 

[JamesW]

Balance the CSI and put the TA wherever it stabilizes the pH.

 

[mberlew]

I've never tracked CSI before but just did and it says 0.15 which says is balanced. Given that, are you just saying not to trust what either PoolMath or the TF-100 instructions say, and instead increase the TA such until the PH stays stable (right now PH does seem to be rising regularly)?

 

[JamesW]

Higher TA causes pH rise.

Drop the pH to 7.8 until it stays there.

If the pH gets to 7.9 or 8.0, drop it to 7.8 and not lower and you will know that the TA is correct when the pH stops rising.

 

[ajw22]

There is no right or wrong value for TA. TA can be whatever gets you the desired pH response and CSI. So a TA number itself is never the goal. TA is a tool to achieve other water chemistry effects.

The TFP TA values are given with more nuanced consideration of the other recommendations then TF-100 and others. Also most in the pool industry assume Trichlor is used to chlorinate pools. Trichlor contains acid which lowers pH and TA. Thus the recommendation is to keep the TA high to offset the acid effects ofTrichlor.

TFP methods do not recommend the use of Trichlor and assume better pool owner education so a lower TA can be recommended.

TA - Further Reading

www.troublefreepool.com

 

[duraleigh]

I assume I should trust PoolMath?

Yes. The Tf-100 instructions are not as up to date as we have lowered our suggested values this last year. This forum learns more and more about TA as time passes and the advice above is solid.