Why Does My Alkalinity Keep Going Up?

by Genaro Castro
(Elk Grove, CA, USA)

I have a 30,000 gallon salt water system with a cartridge filter. My pool is two years old and I've always had problems with the alkalinity.

It's extremely hard to keep it down, it keeps going up to about 240 ppm, it's even been up in the 300 ppm range.

Thanks for the question Genaro

Pool alkalinity is one of those tricky things about water chemistry. That, along with chlorine, is the biggest problem people have with their pools.

There are normally two reasons why alkalinity increases, and they both come from outside influences:

1. Too much sodium bicarb is being used

2. High fill water alkalinity

I would first ask what is your pH level? Is it constant, between 7.4 - 7.8ppm, or does it bounce around? How much bicarb are you using?

If you're using bicarb to raise the pH level, try using either soda ash or 20 Mule Team Borax. These will raise the pH without much happening to the alkalinity.

Then there's the fill water. Are you on city water or on a well? Have you tested the fill water? If the alkalinity of the fill water is high, you've found your problem.

Are you testing the water yourself with a good kit? I use and recommend the Taylor K-2006 kit.

Pool Water Testing

Water Testing Kit

Have you had your water tested by a local pool store to verify your findings? You could do this. And stop if you're using test strips. Get a good pool water test kit.

Here are the alkalinity pages to look over:

Pool Alkalinity

Total Alkalinity

Look over the above info. and if you still have questions please feel free to contact me again.

To post a reply, or if you have a similar question, you can see your post "Why Does My Alkalinity Keep Going Up?" on the Q&A page in the "Alkalinity" category.

Swimming Pool Questions & Answers

Check back to this post for updates or answers.

Hope this helps and good luck with your pool.


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High Alkalinity

by Joe

My alkalinity was at 200. All other measures were good and in range. I added 1 litre of m acid. But I did not shut the pump off.

Covered pool and this am the alkalinity is at 230ppm. Can you explain this please.

Thanks for the question Joe

Be sure you're using a good test kit like the Taylor K-2006. This will give you the numbers you need.

According to my calculations 1 liter is equal to about 1 qrt. or 35 oz. of acid. This should reduce a 15,000 gallon pool's TA 10ppm. The question doesn't state how big the pool is so I can only go on the charts that I have.

It is odd that the TA would go up after adding muriatic acid. Be sure you're using the correct amount for your pool and use fresh acid. The TA will never increase without some kind of outside influence such as heavy rain, adding high TA fill water, adding sodium bicarb, etc...

Your pH may decrease somewhat after adding the acid. You can either use a process called aeration where you introduce air into the pool to increase the pH. Then there's 20 Mule Team Borax and soda ash. It's 16 oz. of soda ash to increase the pH 0.2 per 10,000 gallons or 35 oz. of borax to achieve the same result.

I hope this has answered your question to your satisfaction.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Alkalinity" category.

Check back to this post for updates or answers.

If you feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of your choice and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.

Have a great Summer.


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