Does adding closing dose of PolyQuat 60 cause problems with pH readings?

[lcd98]

Good Morning,

I started the day with a pH of about 7.5 and I wanted to bring it down a bit before closing so I added about 10 oz of muriatic acid which should have brought it down to 7.4. About an hour later, I added the closing/treatment dose of algaecide. I am getting ready to drain some water before the pool is winterized and did one last pH test to see if it came down at all. The pH readings are off the charts (above 8.2) - a shade of purple I haven't seen before on the test. Please tell me I should ignore it and that it is skewed by the PolyQuat 60.

Thanks,
Laura

P.S. Looking forward to the day when I'll know enough to answer questions instead of always asking them!

 

[JohnT]

No, the polyquat wouldn't do that. High chlorine levels might though.

 

[lcd98]

No, the polyquat wouldn't do that. High chlorine levels might though.

The chlorine is 12 but it was 12 with the pH at 7.5 before I added about 10oz of acid which should have brought it to 7.4. The only other thing I did was add polyquat 60. I've drained my pool to the bottom of my skimmer and I am waiting for the pool company to come close it. Should I add more acid to bring the pH down before they do? Thanks.

 

[JohnT]

The chlorine is 12 but it was 12 with the pH at 7.5 before I added about 10oz of acid which should have brought it to 7.4. The only other thing I did was add polyquat 60. I've drained my pool to the bottom of my skimmer and I am waiting for the pool company to come close it. Should I add more acid to bring the pH down before they do? Thanks.

You can't trust your pH test with the chlorine that high. Don't add any acid until you can get a test done with lower chlorine level.

 

[lcd98]

You can't trust your pH test with the chlorine that high. Don't add any acid until you can get a test done with lower chlorine level.

Thanks. They are coming to close the pool this afternoon. Are you saying I should wait a while (maybe a week), open the cover, test the chlorine and if back in the 5 ppm range, test the pH? If I have to add acid then, any advice on how I would mix it into the pool since everything will be winterized?

 

[JohnT]

Thanks. They are coming to close the pool this afternoon. Are you saying I should wait a while (maybe a week), open the cover, test the chlorine and if back in the 5 ppm range, test the pH? If I have to add acid then, any advice on how I would mix it into the pool since everything will be winterized?

You can't add acid after you winterize. You are going to have to stay wherever your pH is now if you close, but there's no easy way to know what that is until the chlorine drops.

 

[lcd98]

You can't add acid after you winterize. You are going to have to stay wherever your pH is now if you close, but there's no easy way to know what that is until the chlorine drops.

Thank you. They ended up running late so I pushed my closing to the next day (Friday). As a result, I was able to retest my water. My FC went down to 7 and my pH went down to 7.4 which is where I expected it to be after adding the acid on Thursday. Thanks again for your help. Have a nice weekend.