High pH and low TA after SLAM

[Horanis]

Hello.
I am closing the pool in the next 2 days.
Prior to SLAM, my pool's pH was 7.2 and TA was 50. I used Pool Math app and added 11 oz soda ash in the skimmer to make pH 7.4. I left the pump to recirculate for an hour then I SLAMed my pool. After 6 hours of recirculation, I retested pH which is way above 8 but TA is 60. I read that high chlorine can give falsely high pH.
Do I need to add MA or just close it for now and retest next spring?

Thank you.

 

[cowboycasey]

This is great, you are seeing what happens to your water when you get into this and you asked a great question...

You should have left your PH at 7.2 and TA at 50.. both of those are just about perfect, yes a little low but not bad at all... Your PH will rise very slowly in this range, this is exactly where mine is and I only drop PH 1 or 2 times a year...

When you added the soda ash it raised both so you will need to lower both using muriatic acid.. Go for a 7.2 PH and then close it

 

[sktn77a]

Yes, a high chlorine gives a falsely high pH reading. Here's a brief summary of testing issues:

12 Simple Pool Water Testing Fails to Avoid | InTheSwim Pool Blog

12 simple pool water testing pitfalls to avoid. You could be making these simple pool testing mistakes and not even realize! Dr. Pool pool water test tips!

blog.intheswim.com

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How high is your chlorine? Unfortunately, in the current cooer weather, the chlorine probably isn't going to go down quickly. I'd go easy on the MA until the SLAM chlorine has come down.

 

[Horanis]

Yes, a high chlorine gives a falsely high pH reading. Here's a brief summary of testing issues:

12 Simple Pool Water Testing Fails to Avoid | InTheSwim Pool Blog

12 simple pool water testing pitfalls to avoid. You could be making these simple pool testing mistakes and not even realize! Dr. Pool pool water test tips!

blog.intheswim.com

.

How high is your chlorine? Unfortunately, in the current cooer weather, the chlorine probably isn't going to go down quickly. I'd go easy on the MA until the SLAM chlorine has come down.

Prior to SLAM, FC was 17 with CYA of 40. I added around ~25 oz of MA and pH is now back to 7.2-.7.3 and TA is 50. It is hard to tell if high pH was due to SLAM or soda ash I added. It was my fault that I did not retest pH prior to SLAM and after adding soda ash. As you said, it would take a while for chlorine level to go down. I already closed the pool this weekend. It is my first time closing. Wish me luck