pH constantly on the rise

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C

capn7

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Mar 6, 2013
21
Phoenix, AZ
Greetings!

I have been working on getting my water right, and recently dropped TA from 170 to 150 to 125 and now to 100 (at 100 for 2 weeks now). However, no matter what I do, my pH seems to be rising by about 0.2/day. I'll chase it back down with acid, and it immediately starts rising again. After reading around here, I checked for any air leaks and see none (no bubbles whatsorver after the first minute or two of the pump starting up) and no returns breaking the surface. No water feature, and the aerator is off. I also read somewhere that a high TA might cause the pH to rise like this, but at 100, I wouldn't think that should be an issue.

I typically chase pH down to around 7.5, and within a few days, it's up to around 8.0-8.2.

The desired TA number seems to be "70-90+" but I'm not sure HOW MUCH "plus" is acceptable. :) Should I try lowering the TA even more to get the pH to remain steady? Or is this daily drift of ~0.2 to be expected? I sure hope not, because I'm dropping more acid than an addict.

This morning:
FC=4.6; CC=0
pH 7.9 (up from 7.5 48hrs earlier)
TA=100
CH=350
CYA=35

For acid, I'm using 14.5% MA, and chlorine is liquid sodium hypochlorite 10%. Complete refill about 2 months ago. I'll add to my signature, but this is in the Phoenix area.
 
For what's worth, the places around me that sell the 14.5% MA sell it for about the same cost as the 31.45% MA. The independent pool stores sell it the cheapest around my area. If by chance you have recently plastered the pool, the rise could be from uncured plaster.
 
Thanks, Richard!

Well that type of pool personality doesn't sound very pleasant. It's addicted to acid, and what a costly habit that is. Would you suggest I force the TA down to something lower, maybe 50-75? Or will adding a little bit of acid for small pH adjustments, over time, lower the TA on its own? The previous times I dropped the TA, I had to do it with copious amounts of acid (bringing pH down to around 7.0-7.2), and the smaller pH adjustments (usually adding around ~30oz MA at a time) don't seem to budge the TA at all.

ping - I haven't seen anything higher than 14.5% here, but then again, I didn't know to look any harder than I have. I'll keep a closer eye out for something stronger, as that would be WAY more convenient. I'm sure LPS here would charge an arm and a leg for it, but I'll check anyways. Thanks for the tip!
 
Do you have an autofill, or are you having to add water often? If yes, what is the TA of the fill water?

I would continue to lower TA, you can either do it quickly using the aeration method, or just keep a close eye on your ph and do it like you have been.

I would look for a 31.4% MA source, I the end that concentration is usually cheaper % for %.
 
Do call your pool stores for the price of 31% MA. You may be pleasantly surprised, after all, it is a product that they probably move quite rapidly and they probably compete with other pool stores.
 
I live in Palm Springs and my pool has the same "personality" as yours. There are several issues-high evaporation rate, high CH and high TA in the replacement water. My first plan of attack was to keep my TA below 60, but the pH still climbs (as does the TA). I finally gave in to using trichloro pucks and they do make a difference! However, you must keep your eye on the CH and CYA when using these. I have come to the conclusion that investing $50 into a sump pump and doing partial drains during the hot months will save me both time and money, as I am no longer chasing the acid and chlorine daily. Our water rate is reasonable, but YMMV. I hope this helps.
 
Sorry guys, I goofed. I quoted that TA from (a very poor) memory while on the road earlier. My replacement water TA is 170, it's the CH that is 300-325. Supply pH was 7.9 this morning; the pool keeps heading up to the neighborhood of 8.0-8.2.

I just got home and dropped some MA in there to push the TA down to around 75-80 (currently at 100) and should have a pH of ~7.2 in the morning. I won't even aerate, and if history repeats itself, the pH will be sky high again within 3 days. :( Hopefully the lower TA slows that down a little.

Please let me know if that revised supply TA changes your suggestions. If not, and the lower TA doesn't do me any favors, I might just look into that acid feeder Jason mentioned, and the higher % MA.

Again, sorry for the misinformation earlier! I truly appreciate all of your patience and helpful responses.
 

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No, advise remains the same. My TA was 170 out of the gate, took me 3 weeks to get down to 60. Although the TA is low, the pH still rises. Even with triclorol pucks.

I just went through a nightmare acid wash for the calcium scaling as I couldn't keep my pH at 7.4. I don't wish this on anybody :-(
 
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