Rapidly dropping alkalinity and 13# Baking Soda only raises it by 10ppm

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pflood4150

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Mar 3, 2016
32
Gold Canyon, AZ
A couple of weeks ago my alkalinity was at 90, and when I tested it a week later it had dropped to 20. I put in 6 lbs of baking soda which raised it to 30, followed by another 3.5 lbs which brought the TA to 50. The next day I put 13.5 lbs in and when I tested the next morning the TA had only reached 60. According to the pool calculator, that should have raised it by 74, not 10! All in all I have put in 27lbs of bs into the pool in the last week and the TA has gone from 20 to 60. What is going on?

The ph is typically at 7.8 every morning and I add 8-12 oz of 31% acid in order to bring it down to 7.5. I am using liquid chlorine and keep it at 4 ppm. My cya is 50, and CH is 280. It had rained heavily around the time this problem started.
 
pflood4150 said:
A couple of weeks ago my alkalinity was at 90, and when I tested it a week later it had dropped to 20. I put in 6 lbs of baking soda which raised it to 30, followed by another 3.5 lbs which brought the TA to 50. The next day I put 13.5 lbs in and when I tested the next morning the TA had only reached 60. According to the pool calculator, that should have raised it by 74, not 10! All in all I have put in 27lbs of bs into the pool in the last week and the TA has gone from 20 to 60. What is going on?

The ph is typically at 7.8 every morning and I add 8-12 oz of 31% acid in order to bring it down to 7.5. I am using liquid chlorine and keep it at 4 ppm. My cya is 50, and CH is 280. It had rained heavily around the time this problem started.
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How are you testing? It should take well over 1-1/2 gallons of muriatic acid to drop TA 70ppm.

What is your pH?
 
domct203 said:
How are you testing? It should take well over 1-1/2 gallons of muriatic acid to drop TA 70ppm.

What is your pH?
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10oz MA (OP quoted 8-12) x 14 days (OP quoted a couple of weeks ago) - 140 oz. Not quite 1 1/2 gallons but working on up to it.

General consensus is to manage the pH and let the TA settle where it provides the best pH stability for YOUR pool. There is no one answer for all pools. The recommendations for TA should be considered guidelines not targets.
 
peirek said:
10oz MA (OP quoted 8-12) x 14 days (OP quoted a couple of weeks ago) - 140 oz. Not quite 1 1/2 gallons but working on up to it.

General consensus is to manage the pH and let the TA settle where it provides the best pH stability for YOUR pool. There is no one answer for all pools. The recommendations for TA should be considered guidelines not targets.
Click to expand...

All tests done using Taylor K2006 kit. Surely the amount of baking soda added should have raised TA considerably by now?
 
I would stop and reevaluate this situation. You added enough baking soda to raise your TA by over 130 ppm. If the amounts are correct, and the volume of the pool is correct, it is there. No matter what. If you continued to add the acid each day (which really seems excessive too) that would have consumed at most 20 ppm TA during that week.

Are you having to manage CSI due to CH buildup? If not, I would stop with the acid additions and see if the pH stabilizes. Only add the acid if you get pH of 8 or higher.
You should not have to add that much acid each DAY, even with our evaporation.

Do you have fountains, bubblers, sheer descents, etc running every day?

Good luck.
 
In the past 2 weeks I have added total of 2 gall 34%acid and the ph has never gone below 8! Since adding 34 lbs of baking soda over the same period my TA is now 90 which should be ok. A week ago we had over 1" rain and the water temp has been a high of 88 and morning low of 83. During the past 2 weeks the waterfall and aireator jet were off. My Taylor r 0004 phenol is less than a year old and has been stored correctly so have to assume that the ph reading is correct as when I have checked it with the oto test it has shown high ph as well as the Taylor kit. Meanwhile the water looks crystal clear. Cannot understand why so much acid has been needed as prior to this problem I had no problem in maintaining ph at 7.5 with adding about 8oz acid every other day.
 
Adding 34 lbs of baking soda to a 12,000 gallon pool would have raised your TA by almost 250 ppm.
Adding 2 gallons of 31.5% HCL would have lowered your TA by 83.

That leaves you with a TA of 165 plus whatever you started with.

I suspect that there's something wrong in your TA test.

I'd say quit testing TA for a while and concentrate on the pH until you get it down to where it needs to be.
 
For the past week every morning the ph has been 8+ and I have added 16oz acid every morning and one day same at night, but the ph seems to stay at 8+. I have never had that problem in past seasons and the only thing which is different is that we have had a lot more rain this year, which is very alkaline.
I agree with Bama Rambler's logic in theory. My Taylor R-008 green reagent is about 3 years old, I have not tested TA for a week as I am concentrating on getting the PH down to 7.8.
 

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Just tested my TA again and it was 150, so I took a sample to pool store and they came up with 140. It seems that my test kit is close to accurate but my TA has gone from 90 to 140-150 in a week without adding baking soda, but 1" of rain fell in that time. Meanwhile PH remains at 8+ despite adding 16os MA a day to a 13K pool.
Also the pool store showed Dissolved Solids at 4100 despite the water having bee changed 4 months ago. Could that be causing my problems?
 
I hate to say this, but you really didn't confirm the validity of your test. You only confirmed that it's no better or worse than the pool store test.
What did they say the pH was?

You say that your rain water is very alkaline, but it actually has a TA of less than 10 ppm, so rainwater isn't raising your TA.

As I said before, don't worry about the TA, just keep adding acid until you got to the pH you're shooting for.
 
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