The pH drifts upwards in a fairly short span of time

[TheElbow]

I hope you don't mind me piggybacking on this post, but I came here to post the same question.
Post split to a new topic. Yes we mind. JasonLion

TA = 100-110
pH = drifts up to 7.6-7.8 within a week of me bringing it to 7.4ish
CH = (can't recall my reading last night, but likely 200ish)


I've found over the past month or so that the pH drifts upwards in a fairly short span of time. My TA was around 140, so I calculated how much acid to use to bring it down, then let the pH rise naturally. But now I find I've been adding acid each week to get the pH back in line. The worst thing is, I haven't really used the pool that much at all. Maybe twice in the past month!


Any thoughts?

 

[JasonLion]

Lower your TA down to around 60 to 70 and see how that does.

 

[ComputerGuyInNOLA]

A lot of things contribute to PH rising. Mine goes from 7.2 to 7.8 in five days like clockwork. I have two waterfalls, a sprinkler to cool the pool, a SWCG, and new plaster all of which contribute to rising PH.

 

[Richard320]

Once a week isn't bad for adjusting pH.

Methinks you doth protest too much.

 

[sarahspins]

I adjust mine weekly - I think expecting to never have to adjust pH just isn't realistic. Mine makes about the same change over a week.

 

[pragmatic]

Same weekly regime here as well.Now that I know my pool,I just add 9oz MA every week and check only every 2 weeks. Always right on the money. Also. Keep in mind bleach has a pH of about 11.5-12. That's adds to the drift too.

 

[RobbieH]

Elbow, post up all your pool specifics. Do you have features (slide, fountain, waterfall), salt water chlorine generator, etc.?

I have to adjust mine once a week, a gallon a week, and that's with borates at 50 and TA of 70.

 

[HouTex]

Elbow, post up all your pool specifics. Do you have features (slide, fountain, waterfall), salt water chlorine generator, etc.?

I have to adjust mine once a week, a gallon a week, and that's with borates at 50 and TA of 70.

I thought I had it bad. I add about a quart of MA every week with borates at 50 and TA of 70.

 

[tcat]

Ditto

Elbow, post up all your pool specifics. Do you have features (slide, fountain, waterfall), salt water chlorine generator, etc.?

I have to adjust mine once a week, a gallon a week, and that's with borates at 50 and TA of 70.

I thought I had it bad. I add about a quart of MA every week with borates at 50 and TA of 70.

 

[RobbieH]

You are adjusting a 9000/15000 gallon pool. Mine is 44,000.

 

[HouTex]

You are adjusting a 9000/15000 gallon pool. Mine is 44,000.

Noticed that after I posted. I have it worse!!

 

[RobbieH]

I don't have fountains or spa. That's why.

 

[TheElbow]

Elbow, post up all your pool specifics. Do you have features (slide, fountain, waterfall), salt water chlorine generator, etc.?

I have to adjust mine once a week, a gallon a week, and that's with borates at 50 and TA of 70.

Here are my specifics:

20,000 gallon pool
No water features
DE filter with fiberclear
Water is new (3 months) but the plaster and pipes are old (potentially 30-40 years!)
Pump is variable speed Pentair (new as of March)

Chem:
TA: 100-110
Hardness: can't recall, but "normal" by my test strip standards. 200 ppm?
CYA: 40-50
Borates: ??? (Just learned about this variable and I'm wondering if checking and adjusting this might help stabilize mt pH)
Combined Cl: 0.5 ppm
FC (as of yesterday): 4-5ppm


I'm using bleach for my Cl source, and have been using muriatic acid to adjust pH down weekly. Tabs occasionally.



In light of all your responses, I'm surprised to see that having pH drifts this frequently is "normal." I assumed that with a good TA, the pH would only shift over longer periods of time and/or with heavy use. If weekly shifts of 0.4ppm is normal, than I suppose thanks to all of you for letting me in on that information.

All the same, I'm going to check out my borates anyway, to satisfy my curiosity.


If my pool/chem details show anything as being odd, please let me know.

Thanks!

 

[Casey]

by my test strip standards.

So we have a stripper eh?

You should really consider investing in a reliable test kit as strips can be unreliable.

 

[TheElbow]

by my test strip standards.

So we have a stripper eh?

You should really consider investing in a reliable test kit as strips can be unreliable.

No I have the TF kit, but I didnt have the hardness reading handy and the strips were the last time I measured it (kit reading was a few weeks back)

 

[Casey]

Well, it's good to know you have a test kit!

 

[JasonLion]

Lower your TA down to around 60 to 70 and the PH drift will slow down significantly.

 

[TheElbow]

I have no problem doing this, but isn't that a low TA? Won't it cause the pH to swing more wildly?

 

[Richard320]

I have no problem doing this, but isn't that a low TA? Won't it cause the pH to swing more wildly?

It will get down there eventually if you keep adding acid to adjust pH.

 

[JasonLion]

If you are using trichlor tablets as a chlorine source, then yes that is way too low a TA. But if you are using bleach, liquid chlorine, a SWG, or cal-hypo, then the recommended TA is 60 to 80 (or 70 to 90 depending) and your TA is too high, thus the PH drift.