TA effect on pH -- can LOW TA cause pH rise?

[lalittle]

I read that if the TA is too high it can lead to the pH creeping up, but I'm curious if pH rise can also be caused by having the TA to low. My pH is constantly going up -- I have to add a does of acid (i.e. to drop pH 1 ppm) at least twice a week if not more to keep it at 7.4. My plaster is probably between 2 and 3 years old now, and I'm told that this is long enough to no longer have an effect on pH. My TA hovers around 60 or a bit higher, which I read was okay, but I'm wondering if this could helping the pH constantly rise, and if it's worth trying to raise the TA a bit.

I use a combination of pucks and liquid chlorine in a non-SWG pool.

I've noticed the same effect for the entire year that I've been here -- i.e. regardless of my specific chemical balance I see the same pH rise -- but my current test results are:

FC - 6
CC - 0
pH - 7.4
TA - a bit above 60
CYA - around 65
CH - 400 ish

Thanks,

Larry

 

[JohnT]

Low TA can cause the pH to be unstable when trying to adjust, but won't cause a steady rise. How do you chlorinate?

 

[jblizzle]

Do you have a waterfall / deck jets / etc? Aeration can cause the pH to go up.

 

[lalittle]

Chlorination is a combination of pucks and liquid. I try to use enough pucks so that I don't need to add chlorine more than twice a week, and they keep the FC level from dropping too fast.

I don't have any waterfalls or deck jets. I do have a spa with an air intake for some bubbles, but there is no blower on it. Also, we don't use the spa every day, and when we do use it, it's typically only for an hour or so on average. My Kreepy Krauly does pull in a bit of air -- I can see some fine bubbles at some of the returns. Could this be enough to cause such a constant, steady pH rise? I see some people saying that they only add acid a few times a season, which is a vast difference when compared to the two to three times a week that I need to add it.

Larry