Alkalinity and pH drifting down when normally drifts up..

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K

kjdo

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Oct 3, 2012
45
Small Town Indiana
this is our second year for our pool and normally I found that the pH and Alkalinity drifted up and I would add acid and all would be good. However, it they have both drifted down and I don't know the cause. Granted, I know I can fix it, but I want to be sure there isn't another problem that I am missing before I put a bandaid on the current problem. Can anyone help?

Currently:
FC 6
Alkalinity is 70
pH is 7.2-7.4
CYA and Calcium are WNL
 
Re: Alkalinity and pH drifting down when normally drifts up.

Please provide your CYA & CH & CC levels. They're needed to properly diagnose your water chemistry.
What is your chlorine source, just the SWCG, or are you using any supplemental CL; bleach/liquid CL, di-chlor, tri-chlor, cal-hypo?
 
Re: Alkalinity and pH drifting down when normally drifts up.

FC = 7
CC = 0
TC = 7
TA = 90
CH = 130
CYA = 70
Salt = 3750
pH = 7.4

Last night I added Alkalinity increaser and everything is measuring OK now. I know the salt is a little high, but I will be backwashing in a few days and diluting/refilling with city water at that time. But, my question remains about why my pool is acting differently this year. Last year was VERY HOT and DRY and we had the pool cover open every day. I tested two times per week and the only thing I had to do last year was add acid because the pH and Alk drifted up CONSISTENTLY. This year, it is cooler, cloudy a lot and the pool is open about half of the time. I just don't want to miss some big warning sign, since the pH and Alk have drifted down in the last few weeks.
 
Re: Alkalinity and pH drifting down when normally drifts up.

It's drifting down, does it just hit a certain point and stay, or does it keep plummeting unless you up it? Are you adding anything to bring it back up?

Less heat, less UV and less bather load equals less CL demand. Which translates into less runtime of your SWCG which means less areation, so pH doesn't rise as easily, if at all. More use of the cover reduces outgassing which also has an effect on pH as well. IIRC
 
Re: Alkalinity and pH drifting down when normally drifts up.

last year was add acid because the pH and Alk drifted up CONSISTENTLY.
Click to expand...
That is certainly what would be considered normal.

By far, the common cause of lowering pH and TA is the use of pucks....which you do not use.

The weather should have no significant affect. I cannot offer a good explanation of what you are observing. I would suggest that you use 20 Mule Team Borax from the Grocery store to raise you pH and TA simultaneously. It's the best product for that particular job.
 
Re: Alkalinity and pH drifting down when normally drifts up.

y_not said:
Jblizzle,
The OP's sig says it's a vinyl IGP.
Click to expand...
Really? I looked at the signature on tapatalk and it just says "IG" nothing about vinyl.

EDIT: hmm looks like this beta software release is not showing the full signature :hammer:
 
Re: Alkalinity and pH drifting down when normally drifts up.

I raised the alkalinity with alkalinity increaser. It is an in ground pool, it has a vinyl liner, it is only two years old. I do not have any pucks in the pool ( I don't even know what that is). I have considered the 20 Mule Team Borax, but I was afraid that would void warranties.

I have not tested the fill water, but need to check ALL components of the fill water just to know the calcium, pH and alkalinity.

Maybe y-not hit the nail on the head. Although I do not know if it would continue to drift down if I didn't treat it, I check at least 2 times per week and make adjustments immediately. All of the things mentioned (Less heat, less UV and less bather load applies to us this summer. It was stated that this equals less CL demand. Which translates into less runtime of your SWCG which means less aeration). Although the PUMP is running all the time, so I'm not sure about the less aeration. We have had the cover on the pool more which was stated to reduce outgassing which also has an effect on pH as well.

Thanks to everyone for their responses, it is much appreciated.
 

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Re: Alkalinity and pH drifting down when normally drifts up.

Having the cover on more this year may be part of it. The cover reduces the amount of CO2 out-gassing, so instead of a slow ph rise like last year, that increased cover time (and less swimming caused aeration) changed the balance slightly to a net ph decrease. Raising the TA (like you did) may help.
 
Re: Alkalinity and pH drifting down when normally drifts up.

I had the same problem last week and found the cause of my problem in an unexpected place....A critter in the return line....ph was drifting down, not up as usual with the SWCG. I also noticed my CL would crash to near zero every couple days, causing me to add bleach to supplement the SWCG. When the pool started to cloud (July 3rd, with 50 people coming for a party on the 4th!), I popped the top off the sand filter, thinking I could have channeling through the sand, as this was a problem for me in year 1 of pool ownership (this is year 3), back when we let my son's Labrador retriever swim every day. The dog is now banned from the pool and channeling wasn't my problem, this time. It was a MOUSE! As I adjusted valves at the pool pad, a well-bleached mouse carcass came through the line and got caught in the pump basket. Apparently, the strainer in my skimmer basket had become dislodged at some point and the mouse was sucked into the skimmer return line, where it remained trapped at the junction for quite some time, given the look of the remains. Since removal of the mouse fixed the problem, I'm blaming the little critter. I guess the lesson is that organic matter can get into the strangest places in our pool systems and can be difficult to find and remove. The mouse was small enough to get sucked into the skimmer, but too big to get past the partially closed valves at the equipment pad. Part of my routine going forward is to fully open skimmer and return lines from time-to-time, so anything caught in the valves can flow on by....

The good news is that by catching the problem early on, the water cleared overnight and we had a great 4th of July Party with a sparkling pool! My pH is back to drifting up a bit, as normal, requiring about 16 oz. of MA a week to keep it right (the only maintenance chemical I need!)
 
Re: Alkalinity and pH drifting down when normally drifts up.

Thank you. If the problem persists, I will look into this as a possibility. Creeps me out to think of dead critters in the pool water. Sounds like I also need to learn about channeling. Our lab swims when we swim.
 
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