rising pH

[pandan74]

Several weeks ago my pool was refill after re-plastering. Everything looks good, except pH rises on daily basis. I need to add acid almost every day to keep pH in range. Do you know why is that? Also TA is going down not as fast as rising pH but still. In the last 8 weeks I had to add baking soda twice already because TA dropped to 60. When adding baking soda I'm increasing pH, so adding more acid to lower pH and Ta lowers too. ..... and the circle is closing. Any ideas, tricks, tips?
Other values:
FC - 2
CYA - 40 (yes will be increased, working on it)
TA -80
CH - 375
temp 89F
salt - 3600

 

[mknauss]

Do you know why is that?

Because of the plaster. Be sure to let the pH rise to 8 and only lower it to 7.6. TA let it fall to 50 ppm before doing anything.

 

[nieuport17]

I have a new plaster pool and doing the same thing, adding 2 cups of acid everyday (for the size of my pool) to keep the pH to 7.6, then every 3rd day I have to add a cup of baking soda, to keep the alk at 50-60ppm range.
I have a water fall, so the aeration causes the ph to up too.
The pool guy that the pool builder hired, just want to dump a (or 2) gallon of muriatic acid in, and come back a week later. I was like, no, I will do it slowly everyday.

 

[texasAUtiger]

I’m about a month in with my plaster pool and it’s the same. It pretty consistently needed 18 oz a day for the first 3 weeks, now it’s down to about every other day, sometimes every third day. It is all part of the chemical process occurring as your plaster cures, and my understanding is this will continue throughout the first year, although at decreasing rate of acid usage, generally.

My fill water had a TA of 300 (!), but today the pool TA was down to 130, so it is slowly coming down towards the target TA as this acid is added over time.

 

[pandan74]

It's been 3 months and still adding acid. It looks like TA stable now at 70-80 but need to add acid every other day.

 

[texasAUtiger]

About two months in and my TA stays around 110. I’m adding 18 oz of acid every day or every other day. pH is fairly stable but hoping this helps bring that TA down. The main trouble is the water I add on a weekly basis has such high TA. It will get there though…