Alkalinity won’t rise above 90

[PoolStored]

How do I stabilize the pH so it doesn’t swing? It was 8.2 and I added acid and now it’s 7.4 (good). Tomorrow it will be 8.2 (or close) again. I never had this issue before we re-plastered the pool.

You can't right now. The only thing you can do is to manage your pH.
New plaster will cause pH rise, and likely will settle down over time. pH rise from new plaster may continue for 6-18 months.

 

[mknauss]

I just never had to do this before the replaster.

I suspect you were using trichlor tablets then, correct? They are acidic.

 

[tanksjeep]

I suspect you were using trichlor tablets then, correct? They are acidic.

Yes ,I was and I’m using them now.

 

[mknauss]

TriChlor - Further Reading

www.troublefreepool.com

How to Chlorinate Your Pool

Before chlorinating your pool, you should know these simple tips. Learn the best way to add chlorine to your pool.

www.troublefreepool.com

 

[YippeeSkippy]

Chlorine pucks are going to cause you grief in short order. First, Pucks contain CYA, which will build up fast and requires water exchange to get rid of.
Secondly- if you buy the ones from Lowes or Costco (Any with the word "Blue" in the name) usually contain Copper. Copper stains- No Bueno! Avoid all the Clorox XtraBlue chlorine and some of their other questionable products.

For your location, a salt water device would be ideal.

Maddie