PH won’t go down, what gives?

[Eight8Mama]

Fired my pool guy a while back and got a new guy. Long story short, our pool equipment is all being used at our rental and I’m not buying all new stuff, so relying on pool service until the lease is up and I can retrieve my stuff and go back to caring for the pool 100% myself. I have however taken more of a roll in balancing the chemicals because we have a problem and him coming once a week isn’t enough maintenance right now.

To make matters worse, while we were out of town, our pet sitter turned on the pool filler and forgot to turn it off...FOR A WEEK!! We live on acreage so no one noticed and we came home to a flooded property and pool with essentially no chemicals.

So fwiw the salt cell and filter have both been cleaned.

Pool guy tested and advised us to put in 11 bags of salt and 8 lbs of CYA. We did that and although the display is reading 3100 ppm salt level, pool guy tested it last week over 4000.

This is what I get every time I test no matter how many gallons of acid I pour in...

 

[Eight8Mama]

A couple more details...

Pump/salt cell running 10 hours a day. Chlorinator is set to 70%. We did recently have to do the solder joint repair on the Hayward motherboard because the cell wasn’t getting power. The motherboard box is kind of hot to touch. It’s right in the Texas sun, but it would be warm/hot without the sun, so we may need to replace it in any case. I’m thinking of unplugging the cell and seeing if I can get the ph under control if the cell is unplugged.

 

[mknauss]

What is your FC? From the FAS-DPD test.

 

[Eight8Mama]

What is your FC? From the FAS-DPD test.

TC and FC appear to be equal and >5ppm.
PH is down to 7.5 now that I’ve added another gallon of acid this morning and let it circulate a couple hours. Problem is, within a couple days the PH trend is it goes back up >8.2.

 

[mknauss]

Do you not have a FAS-DPD test?

The pH color you show appears to be influenced by a FC above 5 ppm if you are using a DPD test kit. Be wary of adding acid based on that test result.

What reagent are you using for the pH test?

 

[Divin Dave]

Thinking the SWG is making your pH rise that quickly and that far is a bit of a far reach.
Depending on the condition of your plaster and the TA, those are the most likely culprits.
However not having any other info about the water parameters or any idea of your pool in general isnt helping determine what might be happening.

Now that you've added enough acid to get the pH into a testable range, you need to fully balance the pool and go from there.