Total Alkalinity

20,000 Gal pool, glass media filter, fibre glass surface, using liquid chlorine.
I had kept my TA at above 100 when I had a concrete surface. Since it was refurbished to fibre glass, the guy who did told me to not worry about TA any longer because of the fibre glass coating, which seemed odd since all the manuals insist that TA is essential to buffer the PH. I nevertheless let the TA slide to around 20 and haven't noticed any difference. Does this make sense to anyone? Appreciate any feedback and thank you.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
In a concrete/plaster pool very low TA can cause pitting of the pool surface. That isn't an issue for a fiberglass pool. But there are other issues to keep in mind as well. Very low TA allows the PH to vary, though how much that actually happens very much depends on what is added to the pool. If you are using bleach or liquid chlorine or cal-hypo and have TA around 20, the PH will spike up right when you add chlorine and then go back to where it was over the next few hours. That won't necessarily cause problems right away, but it can easily become problematic at some point.

We recommend keeping TA between 60 and 90, usually towards the lower end of that range, in that situation. That will keep any short term PH swings under control.