Question about correct Alkalinity numbers?

[Seanhan]

TF-100 instruction card says Alkalnity for SWG should be .. 70-90

Pool School says...60-80. ( SWG, Fiberglass )

Iam at 90 ...

Why is there a difference and whtch one should i use ??

Thanks...

 

[frustratedpoolmom]

Not sure why there is a difference but 60-90 is acceptable. Having TA higher than those levels simply causes the PH to drift up because the SWG is a source of aeration. Aeration combined with high TA cause PH drift. So simply lower the PH to 7.2 anytime it drifts up to 7.8, and eventually the acid lowers the TA into range as well, and you won't see the PH drift anymore or as often.

In other words, your fine.

 

[thehowheels]

The section on TA I found from the poolcalculator.com explains that TA is calculated differently if you have a SWG:

If you have a SWG, or if you commonly run water features such as a spa, waterfall, or fountain, keep TA on the low side, between 60 and 80. Otherwise levels between 70 and 90 are good.