How long does it take for ph to raise after adding baking soda?

Jun 6, 2015
49
Walkersville MD
Hello. The past 4 days or so, we did a SLAM. Yesterday, FC was 7.5 and ph was 7.1. I added 1/2 large bag of baking soda (7 lbs) to bring ph up. This morning, I tested and fc was at 3.5 and ph only came up to 7.2. I added 1/2 jug of bleach to bring up to 4 fc. If the baking soda worked, should it show up in my test today yet? Or should I add more? Using the Taylor k-2006. Thanks!
 
It is true that PH readings will be erratic during a SLAM. If you just finished, and your FC level is still quite high based on your CYA, it could be throwing that PH reading off. However I see no CYA reading to compare to. So I would suggest posting a full set of test results (FC, CC, CYA, PH, TA) so we can better assist you.
 
The basic issue is baking soda is NOT how you raise pH

pH up - 20 mule team borax

pH down - Muriatic acid

TA up - Baking soda

TA down - aeration and acid...it's process found in Pool School that you must read to make TA change quickly and permanently

On a different subject, you should not test pH when your FC is over 10 ppm....you get a false high reading.
 
Oh, okay thanks. I tested ph yesterday when we were done with our slam - just waiting on fc to go back to around 4. We put enough cya in 2 or 3 days ago to get up to 30. Someone said don't bother testing cya for about a week because it wouldn't show up in there. I looked on pool math and saw soda ash and thought that was baking soda! Hopefully I didn't increase my TA too much.
Yesterday, before I put in the baking soda, there were my readings:
FC 7.5
CC 0
ph 7.1
TA 80
 
Okay, I see now. :) Not to worry, we all get our lines crossed from time to time. Now that we see your most current numbers, you could use a little Borax to get your PH to the recommended level of at least 7.5. You are correct about the CYA not showing up for a few days. But assuming you added enough stabilizer to get you to a starting point of 30, then your FC target would be 4.

Just to make sure though ... you did in-fact pass all 3 SLAM criteria right? We hope. :) So the water is crystal clear and all you are concerned about now is adjusting your PH a bit right? If so, I think you have a good way forward. If you have any other concerns about your water or recent SLAM, by all means please ask.
 
Yes we passed the SLAM test : ) I just put in borax so hopefully that will raise our ph a little. Luckily, our TA only rose to 90 today from 80 yesterday before I put in the baking soda. I don't know why we seem to need to add at least twice the amount of everything recommended on pool math - maybe our pool is larger than we suspect? Thanks everyone!
 
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