Adjusting PH while SLAMing

JibJab

Member
Jun 9, 2019
21
Fort Worth, TX
I began the process of SLAMing the pool yesterday, starting with a 7.4 ph. This morning, I'm testing at 7.7, presumably because of all the 12.5% liquid bleach I added. Should I add muriatic acid now, or wait until SLAMing is done? If so, how long should I wait after adding the acid to add the chlorine?
 

jseyfert3

Well-known member
Oct 20, 2017
253
Janesville, WI
The pH test is not accurate when the FC is above 10 ppm. Do not act on any pH test result taken when the FC is above 10 ppm.

Wait for the SLAM to finish, allow the FC to drop below 10, and retest the pH before adding any acid.

P.S. adding liquid chlorine does not change the pH of your pool.
 

JibJab

Member
Jun 9, 2019
21
Fort Worth, TX
Ok... I guess I'm just scratching my head a little, because using pool math, I added enough chlorine to raise my FC to 20, and this morning it is testing at 5, which makes me think it may be higher?

But, I have done nothing but brush the pool and add chlorine, so I'll have to go with your assessment and ignore the pH for now.
 

HeyEng

Silver Supporter
Nov 7, 2018
393
Oklahoma City, OK
Ok... I guess I'm just scratching my head a little, because using pool math, I added enough chlorine to raise my FC to 20, and this morning it is testing at 5, which makes me think it may be higher?

But, I have done nothing but brush the pool and add chlorine, so I'll have to go with your assessment and ignore the pH for now.
How much time was there between adding chlorine and the test? If it's been a while then the organic material in the pool is probably eating up the chlorine. How are you testing your water?
 

JibJab

Member
Jun 9, 2019
21
Fort Worth, TX
I put the chlorine in last night, and then just tested it now, so about 12 hours. In retrospect, I should have tested a few hours after my last dose last night. So I don't doubt that the FC is now at 5. And this leads me back to my original thought of adding acid.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,069
San Dimas, CA (LA County)
I put the chlorine in last night, and then just tested it now, so about 12 hours. In retrospect, I should have tested a few hours after my last dose last night. So I don't doubt that the FC is now at 5. And this leads me back to my original thought of adding acid.
If the FC is 5 then the pH test is accurate and if you absolutely feel you must, you can add acid. Wait at least fifteen minutes after adding it to add the next load of bleach.