High Alkalinity Dilemma

by Mike Dufala
(Easley, SC)

I added sodium bicarb to raise the pH in my pool.

It got the pH right, but the alkalinity is now very high.

How can I reduce the alkalinity without reducing the pH as well.

And if the pH goes down, how do I raise it without raising the alkalinity?

Thanks for the question Mike

It would be great to have a complete chemical list. It makes the process go faster. I get this alot from pool owners who are battling a high pH and alkalinity problem.

You can raise both the pH and alkalinity (total alkalinity/TA) using sodium bicarb. The TA of our fill water is 30ppm, while the pH is 8.0ppm. This is what I have to deal with at the YMCA pool.

If I put 400 oz. of bicarb. in to raise the TA, then the pH should go through the roof, but it doesn't.

Same goes when I need to reduce the pH. I use acid, but nothing happens to the TA. It's all in how to make the adjustment. Check out these posts:

Chemical Levels Wrong..How To Bring Down Pool Alkalinity..

High PH and High TA

The main thing is to pour the acid in the deep end with the pump off. Very gently brush the bottom to break up any hot spots of acid.

Allow it to sit for 2 - 3 hours, then turn the pump motor on and allow for 1 complete turnover of the
water. This is normally about 8 - 10 hours, then retest. Try to make any adjustments in the evening until the alkalinity is in range.

For every 10,000 gallons of water, to reduce a pool's alkalinity 10ppm, it takes 0.8 qts. or about 30 oz.

There another way to decrease the TA, but you'll be decreasing the pH at the same time. Broadcast the acid around the perimeter of the pool. Again, this will decrease both the pH and TA.

Then you add movement and air to the pool through water features, slides, air compressor etc... This raises the pH through burning off the CO2 (carbon dioxide). Retest and make another adjustment.

I like the first way because when I had my pool route in Arizona I didn't have time to turn the water features on and I didn't have an air pump.

Besides, if I turned something on I would have to go back and turn it off. More driving and time. Being that I don't have the TA, pH, or the size of your pool, you can go here for the charts you need:

Pool Alkalinity

Total Alkalinity

Swimming Pool pH Levels

Pool pH

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.

Swimming Pool Questions and Answers

Check back to this post for answers.

Hope this helps and have a fun and safe swimming season.


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Stabilizer & pH Minus For Low CYA & High pH & TA

by Jennifer

I have an above ground vinyl pool 12' x 30" approx. 2000 gallons with a 600 gallon per hr cartridge filter pump. I run the pump about 12hrs/ day and unplug it when we swim.

The pool was filled with our city water which has Hardness of 800, PH 8.4, 0 CYA, trace FC, 240 TA. My goal is to have safe, sanitary, and comfortable water for my family until it is time to take the pool down in the Fall.

I have been trying to manage several problems at once, while allowing my family to swim during times when the water tests within safe FC parameters. I reduced the PH to 7.5 with dry acid over several days, only to see it creep back up to over 8.0.

I am using 6% chlorine bleach to sanitize daily. My FC holds at night (I have shocked to 10 and 15ppm, daytime target is 3ppm. I often have to add 4oz of Chlorine an hour before my kids swim in the afternoon. Chlorine always drops to 0 during the day, then I add more at sundown.

The water is now beginning to become hazy. I have added 3.0 oz stabilizer to a sock and it is mostly dissolved 12 hrs later. I have no noticeable increase in CYA on test. I need to add more stabilizer, but I also have to keep my chlorine from 0'ing out and my ph is 8.2 today which is too high for swimming.

What order and time interval should I treat? PH? Stablizer? Chlorine? It doesn't seem safe to add all in same day, but perhaps it is. I am at a loss of how to manage these multiple issues safely and simultaneously.

Thank you in advance for your time and help!

Thanks for the question Jennifer and the chemical readings

There are a couple of numbers that seem to be off so I want to clarify it. The pool size is 12X30. If you have 48" walls it would be 9200 gallons. The question says 2000 gallons, but I'll go with 9200.

2nd is the hardness. 800ppm seems a bit high. I know that places in Ohio have higher than 14gpg, but I wanted to be sure about your numbers.

Your TA is much too high. When the TA is high it will chew up chemicals pretty fast. You need to get that down to the range of 80 - 100ppm, 120ppm being the top.

It's 0.8qrts. to lower the TA 10ppm per 10,000 gallons. Your TA is 240 and need to reduce it 140ppm. This is going to require about 2.5 gallons of acid. Add 1 gallon of acid in a bucket filled 1/2 with pool water and stir with a stick. With the pump off, pour into one spot and gently sweep the bottom to break up any hot spots of acid. Allow to sit for 3 - 4 hours, turn the pump back on and FILTER for 8 - 10 hours, then retest and make another adjustment if needed. The pH might decrease because of the acid so be sure to test that as well.

Pool Alkalinity

Total Alkalinity

Next, you need to get CYA into the pool. Shock the pool with Dichlor chlorine. This is a stabilized form of chlorine. Once you reach the 30 - 35ppm mark, stop with Dichlor and go back to regular liquid chlorine. Target range is 30 - 50ppm. It's 1 1/3lbs. of Dichlor per 100,000 gallons to shock.

Be careful when using Dichlor as it can get out of hand quickly. For every 10ppm of chlorine added with Dichlor, you'll raise the CYA by 9ppm. For every 10ppm of chlorine added with Trichlor tabs you'll raise the CYA by 6ppm.

Shock with Dichlor when you turn the pump back on AFTER making the TA adjustment. You can make adjustments with different chemicals, but you need to wait a few hours before applications. FILTER for 8 - 10 hours, then retest and make another adjustment if needed.

Swimming Pool Chlorine

Pool Shock

Pool Chlorine

The pH range is 7.6 - 7.8, but you can go to 7.4. It's 12oz. of acid to reduce pH 0.2 per 10,000 gallons. Broadcast this around the perimeter of the pool with the pump on FILTER. Sweep very well.

Swimming Pool pH Levels

Pool pH

So to summarize, make the adjustment to the TA in the evening. Turn the pump on and add the Dichlor. Retest the TA, chlorine, CYA, and pH after 8 - 10 hours and make another adjustment if needed.

Make the adjustment to the pH with acid.

If you would like personal assistance, I do phone consultations for a donation of your choice. It makes things go much faster. If you choose to not go that route, we can correspond by email.

Contact Me


Hope this helps and have a great Summer.


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Very High Alkalinity Help!

by Julie

I am a new pool owner. The Alkalinity of my pool is 200 ppm! I have watched your video on how to lower it. Very helpful. What is the most muriatic acid that I can add at a time to my pool at a time to lower it to 100 ppm? I'm afraid to add to much at a time. My Ph is currently at 7.2 and Chlorine is at about 3.5. Your videos are great!

Thanks for the question Julie and your vote of confidence. For lowering the TA it really depends on your size pool as to the amount of acid to put in per application. Larger pools can add 1/2 gallon while smaller 10k gallon pools may only need 20 oz.

A general rule of thumb is 12 oz. to reduce the TA 10ppm per 10k gallons. I like to 1/2 or maybe 3/4 that and not put it all in at once. You can overshoot the mark which means adding bicarb to increase it again.

Say you have a 20k gallon pool with a TA of 200ppm and want to decrease it to 100ppm. You would use approx. 150 oz. of acid, but, this may bottom out the pH because acid lowers BOTH the pH and TA. So what can you do? You can start with about 50 oz., filter for 10 hours then retest the pH and TA and make another adjustment. It's this process that a pool owner must be patient and not expect immediate results. You can increase the pH using aeration (slides, waterfalls, air compressor hose in the pool). This causes "out-gassing" which means the carbon dioxide is released through the bubbles and causes the pH to rise. You can also add 20 Mule Team Borax or Arm & Hammer WASHING Soda, not baking soda. These will increase the pH without much happening to the TA.

So, the process is decreasing the TA while increasing the pH using the products mentioned. It does take time and patience but it can work. TA and pH are those things that if you do something to one, to a lesser effect, you do to the other one. It's the nature of the pool beast, so to speak.

I always want new pool owners to get off to a good start. I normally charge $37 for a pool consult but for new pool owners I drop the price to $27 and include all 3 of my eBooks for free.

If you feel your situation is more complex than this, I do phone and/or SKYPE consultations. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias. If you purchase a personal phone consult you'll get all 3 eBooks for free.

Pool Consultation

Clear Blue Pool eBook

How To Clear Up A Green Pool eBook

Swimming Pool Resources

Hope this helps and have a great Summer.


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