What causes TA to creep up?


Well-known member
Apr 25, 2010
Sunny Phoenix AZ
Hey guys,
So about 2 weeks ago I set out to lower my TA to keep ph from rising too quickly.
I was successful in getting the TA down from something like 120 to 65-70ish using a couple cases of MA.
The bright side is that with lower TA it takes less acid to keep the ph down. However, it still takes significant amounts of acid to keep it down every week (1 gal twice a week of 14.5% seems to be the going rate).

Anyways I tested my TA yesterday and was surprised to see it had risen to 85-90ish. Our source water has TA of about 120, so it would have taken a tremendous amount of refilling to make this happen in such a short period of time. What causes your TA to rise quickly?

We have an old plaster pool so it isn't any odd effects from getting a new pool.
I haven't added anything but liquid chlorine and acid (and 50ppm CYA after draining the pool a month or so ago)...

I suppose it could be sampling or testing error - I'll test it again tonite before I add my chlorine...I always sample after the pump has been running at least an hour and I take the sample elbow deep on the deep end in front of a return, for consistency...


Well-known member
Mar 17, 2010
Spring, TX
When you do the TA test, make sure to wipe the dropper after every 4-5 drops from what I have read. Sometimes it can built up static and throw your test off. I always have a cloth and just wipe mine off after each drop. You want to try and get the drops the same size if possible each time.