TA and PH instability

[saschwegler]

Hello all.

I believe I am struggling with a TA and PH instability issue and I don't know what to do about it. Last fall we replaced our 18,000 gallon round pool with a 9,000 gallon oval pool. Since spring I do my normal routine to get all the chemicals stable and everything seems fine to me except my PH climbs about .2 - .4 in about a weeks time. Over the past 3 weeks I have been adding MA to bring down my PH and TA and then aerating. Once it seems everything is good then I would stop. A few days later the PH is climbing again. I have had to do this 2 times over 3 weeks because the PH does not seem to stabilize. I do not have a test for borates but I did try to add a pound or so of Boric Acid to try to assist in stabilizing the PH. It didn't seem to help. Is it possible that the other pool had more borates or something in it so it was more stable? One other noticeable difference between pools is the temperature of the water. My old pool hovered between 72-80 degrees. This pool had already gotten to 92 degrees. Below is the last test done this morning.

My FC's are usually in a decline of about 2-3ppm a day which is about typical for me.

FC: 6
CC: 0
PH: 7.6 (was 7.4 3 days ago)
TA: 110 (was 80 3 days ago)
CYA: 55
Temp: 80

The water looks really clear and all is good otherwise but I already had my PH over 8 twice this season because when I think it is stabilized it really isnt. Is this normal and I have just been lucky in the past or what am I missing? Any advice would be greatly appreciated.

Thank you in advance!

 

[Rancho Cost-a-Lotta]

What's the TA and pH of your fillwater?

 

[PoolStored]

TA: 110 (was 80 3 days ago)

This is not possible, unless you made some addition, either chemical, or added a significant amount of fill water with High TA. Test your fill water as @Rancho Cost-a-Lotta recommended.

In general, this is good advice:

1. TA > 80 --> When pH gets to 8.0, lower your pH to 7.4-7.6. pH will rise. When pH gets to 8.0, lower to 7.4-7.6 again. This will lower TA over time.
2. When TA is between 60 and 80: DON'T lower pH to 7.6. pH will be fairly stable between 7.8 and 8.0. If it is stable at 7.8, 7.9 or 8.0, leave pH alone.

I would also visit the instructions on TA testing. You should add drops until the color no longer changes and subtract that last drop. I would also clean your vials with rubbing alcohol to insure no contamination.

Total Alkalinity

A drop-based test used to measure the alkalinity in water. Alkalinity helps serve as a … Read more…

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[saschwegler]

Fill water? Not sure. I haven't tested it and I haven't reded to refill since mid June or so. We have been getting storms that keep it pretty full.

 

[Rancho Cost-a-Lotta]

I guess that rules out fillwater as a source of your TA rise.

 

[saschwegler]

This is not possible, unless you made some addition, either chemical, or added a significant amount of fill water with High TA. Test your fill water as @Rancho Cost-a-Lotta recommended.

In general, this is good advice:

1. TA > 80 --> When pH gets to 8.0, lower your pH to 7.4-7.6. pH will rise. When pH gets to 8.0, lower to 7.4-7.6 again. This will lower TA over time.
2. When TA is between 60 and 80: DON'T lower pH to 7.6. pH will be fairly stable between 7.8 and 8.0. If it is stable at 7.8, 7.9 or 8.0, leave pH alone.

I would also visit the instructions on TA testing. You should add drops until the color no longer changes and subtract that last drop. I would also clean your vials with rubbing alcohol to insure no contamination.

The only chemicals the pool gets from me is bleach, MA, CYA and Boric Acid (for the first time as listed above). That is why I am so confused. I thought a PH in that range was a little on the high side. Good to know. I will clean the vials. Thank you for that tip.

 

[Bperry]

The only chemicals the pool gets from me is bleach, MA, CYA and Boric Acid (for the first time as listed above). That is why I am so confused. I thought a PH in that range was a little on the high side. Good to know. I will clean the vials. Thank you for that tip.

Your pH rises that fast because your TA is so high.