pH is not increasing

8ightiesfan

Active member
May 26, 2020
36
Canberra, Australia
From everything I have read and been told the pH in SWG pools always increases and you use acid to lower it to keep it in the range.

The pH in my pool has not notably increased in over 2 months. It sits happily at 7.6 and barely increases. Every time I test it it reads 7.6. It *may* have been 7.7 around 2 months ago and I added 500ml of acid but I did that more to confirm my eyes are reading the phenol red test correctly. In the last 6 months I would not have added more than 2L of acid.

Since using TFP methods it has been like this, prior to discovering TFP and early on in pool ownership it did increase and needed maybe 500-800ml of acid weekly. I am certainly not complaining about it. I really just want to know if this is normal for well balanced water?

Cheers
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
15,185
Evans, Georgia
New pool plaster often causes frequent rises in pH as the plaster "cures".....can be months to a year. Then slows down.

My SWG doesn't pull my pH up very often at all. Aeration will do it, but I suspect that since my SWG is almost 3x my pool volume and this allows me to run it on very low settings and still get all my FC, that the pH isn't as affected. My pool's happy place is 7.8.

Maddie :flower:
 

mgtfp

Bronze Supporter
Mar 5, 2020
730
Melbourne, Australia
Pool Size
66000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Astral VX 7T
With your TA at 70, you could well be in the lucky situation that you pH settles somewhere below 8. And from your logs, it looks like you added Trichlor and stabiliser - they are also acidic and would have brought your pH down a bit.

But some of your pH readings don't look reasonable. There is for example a reading of 7.6 at an FC of 21 - at that FC the chlorine is interfering with the pH test, it should look very red, being misinterpreted as above 8.

How old is your test kit? It may be too old.
 

8ightiesfan

Active member
May 26, 2020
36
Canberra, Australia
The pool plaster is certainly not new, the pool is 25 years old

The test kit is also quite new bought in June, however I also have an old 4in1 test kit that I inherited with the pool, I sometimes use this for the pH test only as I find it easier to read the pH test with this kit and I like to compare the pH test in this kit with the pH test in the new kit, though the age of this kit is unknown and likely the reagents are very old. The old kit appears to give a readable test when the FC is above 10ppm when the newer kit will only read to max 8.2, how accurate this old kit is could be debated, though it gives a consistent reading of pH when FC is above 10 to when I test again with the new kit when FC returns to normal.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
22,153
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Your signature says you have a tiled pool. If so, you have little plaster in the grout.

Other folks would not complain about your situation.
 

8ightiesfan

Active member
May 26, 2020
36
Canberra, Australia
Your signature says you have a tiled pool. If so, you have little plaster in the grout.

Other folks would not complain about your situation.
Yes just the grout in between the tiles. Certainly not complaining, just trying to learn and understand as everywhere you read talks about pH constantly increasing and I am not experiencing that.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
34,722
Laughlin, NV
The main source of rising pH is high TA fill water and aeration. A SWCG in itself does not cause pH to rise.

You have benign fill water and are quite lucky!
 
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