My pH adjustments are finicky - anyone else had this happen?

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bedelliott

bedelliott

0
Jun 13, 2017
134
Austin, TX
I need some feedback on making adjustments to my pH. I read somewhere on TFP about not doing full amounts of anything besides when SLAM'ing, so I always do things in stages. Today I needed to decrease my pH by .5 - poolcalculator said to add 26 oz of acid so I added 20. This only brought it down to 7.7-7.8 (after waiting 3 hours with the pump running). poolcalc then said to add 13 oz (to go from 7.7 to 7.5) so I added 12 oz, a little less than recommended even using the lower of my test result. I'm now down to 7.4, after waiting 2 hours & several kids swimming, so I believe it's mixed in well. I'll give it a few hours and test again, just to be sure, before adding some borax but I'm curious if it's just a known fact that pH adjusting is a little unpredictable. And yes, my pool volume is accurate - got it from the builder and all other tests & poolcalc are spot on. In hindsite, maybe poolcalc's initial estimate of 26 oz was accurate, but I'm not sure why it only came half way down (and I repeated this test twice with the same result just to be sure, although I'm excruciatingly consistent when I test). Also, does FC need to be in any particular range in order to adjust the pH the most easily/accurately?
Here are my current #s:
FC 7.5
CC 0
pH 7.4
TA 100
CYA 50
CH 300
Thanks y'all, as always! :)
 
No reason not to do a full adjustment on pH that I know of. pH will rise over time and with aeration/splashing, rain can raise it as well. Every time my pH gets to 7.8 I knock it down to 7.2 and I know I won't have to deal with it for a week or so unless we are having a party.
 
bedelliott said:
I need some feedback on making adjustments to my pH. I read somewhere on TFP about not doing full amounts of anything besides when SLAM'ing, so I always do things in stages. Today I needed to decrease my pH by .5 - poolcalculator said to add 26 oz of acid so I added 20. This only brought it down to 7.7-7.8 (after waiting 3 hours with the pump running). poolcalc then said to add 13 oz (to go from 7.7 to 7.5) so I added 12 oz, a little less than recommended even using the lower of my test result. I'm now down to 7.4, after waiting 2 hours & several kids swimming, so I believe it's mixed in well. I'll give it a few hours and test again, just to be sure, before adding some borax but I'm curious if it's just a known fact that pH adjusting is a little unpredictable. And yes, my pool volume is accurate - got it from the builder and all other tests & poolcalc are spot on. In hindsite, maybe poolcalc's initial estimate of 26 oz was accurate, but I'm not sure why it only came half way down (and I repeated this test twice with the same result just to be sure, although I'm excruciatingly consistent when I test). Also, does FC need to be in any particular range in order to adjust the pH the most easily/accurately?
Here are my current #s:
FC 7.5
CC 0
pH 7.4
TA 100
CYA 50
CH 300
Thanks y'all, as always! :)
Click to expand...

Are you adding borax because you want to add borates to the pool or as a PH adjustment? I wouldn't rush to adjust 7.4 up with borax but maybe just aerate a bit.
 
Thanks for chiming in folks! I'm targeting 7.5 because I've seen where that pH could be helpful in decreasing my FC demand. I've aerated before and it seems less controllable, I suppose I could just test every 30 minutes though. Why aerate vs getting a quick fix with borax?
 
pH always tends to rise in nearly any pool, unless you are consistently using acidic shocks/tablets such as dichlor and trichlor. No sense "wasting" borax when your pH will likely rise anyway.

Attempting to hold your pH at a certain level to decrease chlorine usage is not something that has been taught here at TFP. Chlorine can be marginally more effective at lower pH levels but not enough to warrant trying to maintain a strict pH level. As long as you're between 7.2 and 7.8, inclusive, your pH is fine. With a plaster pool, the resulting CSI level at a given pH, TA, CH, CYA is more important for your pool surface than any effects on chlorine effectiveness.
 
this is where I got my info - copy/pasted from poolschool's "ABCs of pool water chemistry":
PH - Acidity/Basicity

 PH indicates how acidic or basic the water is. PH should be tested daily at first. Once you gain experience with your pool, less frequent monitoring may be appropriate, depending on your pool's typical rate of PH change. A PH level of 7.7 and 7.8 is ideal, but really anything between 7.2 and 7.8 is doing fine, while levels between 7.2 and 8.0 are acceptable for swimming.
 

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I just read up on the "drifting up" stuff, so I'll leave mine at 7.4 and what happens in a week. I'm still interested in hearing if folks have difficulties adjusting their pH based on pool calc's recommendations - my adjustments today (see original post) kind of flew everywhere not in alignment with poolcalc. Thoughts on that y'all?
 
Thanks for the tip, I've always used poolcalculator.com (I didn't know it was no longer supported - why not delete that page then?), but I'll start using the one on TFP, but I just checked and it tells me the same thing about today's activities so no harm done today. And about using the top portion with everything filled in, yes, I did use that, but good check though - this is actually the 1st time I've used the top portion of poolcalc - in the past I've only used the bottom section where it tells you the effects of adding a certain something. duh! :)
 
AimeeH said:
You cannot delete that which you do not own.
Click to expand...

This. It was originally developed by a TFP user/moderator but was subsequently rolled into TFP as Pool Math itself and updated for better accuracy, taking into account other chemical levels in a better way. poolcalculator was abandoned at that point. It has not been updated, formula and calculation, in at least 3 years or more.
 
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