Why Should Sodium Bicarbonate Be Added Moderately Over Time To Reduce TA & Not All At Once

by Brad
(Trinidad and Tobago)

I read in several places that when adjusting TA, it should be done with some degree of patience (1kg per 50,000 litres of water over 4 days), however, no one explains why this is so.

Why is it not recommended to make a 60ppm adjustment in one go?

Thanks for the question Brad

I want to clear up a part of your question. You probably meant for sodium bicarb to increase, not reduce the alkalinity. Muriatic acid is used to decrease TA and pH levels.

To do small adjustment, then test, makes perfect sense. This is normally when you have a very large adjustment to make. If you're TA is 130ppm and you want to get it down to 100, you can do it in one adjustment. It's not a huge difference.

You want to take it slowly when making a large adjustment. Say your alkalinity is 240ppm. Your target TA is 100ppm. That's a 140ppm jump. Many people are hesitant to pour 4 - 6 gallons of acid in the pool.

You don't want to over-shoot your goal. If you do, you'll need to make another adjustment to raise it.

It can also be bad for the pool surface. Pouring 5 gallons of acid into a pool can stain the liner.

I always tell people to make an adjustment, wait for one turnover of the water, then retest and make another adjustment if needed. By doing this in stages, you can see the results.

Many pool owners get impatient and want the results now. They may add acid, wait an hour, then test. They don't get a reading so they add more acid, wait an hour and test again. They just doubled up on the acid. After a full turnover, normally about 8 - 10 hours, their readings are way too low.

Now they're angry that they overshot their target reading and need to make another adjustment that costs more time and money.

You can make a 60ppm adjustment, just be sure your measurements are correct. If you don't have the right measurement, you run the chance of not hitting your target reading.

I also tell people it's much easier to put chemicals in than take them out.

Last year during the YMCA shutdown, I couldn't be there to help with the pool. My supervisor had to raise the TA from 30ppm to 100ppm so he added 150 pounds (68 kg) of bicarb in one shot. It just had to get done "right now!"

He called me and said the TA is now 260ppm and the pH was way too high. It took 12 gallons of acid to get the TA to 100ppm and pH to 7.6. Each gallon of acid is $8. He used more acid in 2 days than I use in 10 months.

In the end, having a little patience, making small chemical additions, and retesting, not only will get you to hit your target, but it saves time and money.

Hope this helps and have a wonderful day.


Comment By Brad


Thanks for your feedback. There was an error in my ques. I meant sodium bicar to increase TA and not reduce. You have answered my question.

Thanks again


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Jan 04, 2015
Alkalinity Low
by: RG

Great website! I have been able to lower my pH using acid. Alkalinity is low now. I may have missed it in this post, but what is the best way to raise alkalinity without raising pH?

The easiest way to raise the TA is with baking soda. It's 16 oz. to raise the TA 10ppm per 10k gallons.

Pump OFF and put the bicarb in the deepest part. Allow to sit for 4 hours then pump back on to FILTER for 10 hours, retest and make another adjustment.

Check the pH as bicarb can raise both the TA and pH. If the pH increase add acid with pump on FILTER and sweep well.

Be patient as this may take a few applications.


Jul 27, 2015
Having a Problem Lowering My TA
by: April & Jason

Hi Robert,

I been watching your channel to see if there was any advice you can give me on my alkalinity levels.I have a 5,300 gallon circular above ground pool... All my other levels are within normal limits, however, my alkalinity keeps going up. Today my chlorine levels were between 2.0 and 3.0, my ph was at 7.5, my Alkalinity levels keep going between 180 and 200, Hardness was at 100, and they CYA was at 150. I tried two different products to lower the alkalinity. Ph down and a pool water stabilizer. nothing seems to be working. what is your advice... my email is Ladyhawk330205@yahoo.com.

Thank you in advance.
April & Jason Brown

Thanks for the question. TA normally doesn't increase on its own. It needs an outside source such as adding too much TA Up or baking soda, or possibly high TA fill water. If the pool's TA is 100ppm but it's being topped off with fill water TA of 300ppm it will dramatically increase.

To decrease the TA you can use either muriatic acid or dry acid which is what I assume for pH down is HYDROCHLORIC ACID. Many times granular acid is sodium bisulfate which I recommend. The one area that caught my eye was using pool water staibilizer to lower the TA. Stabilizer/CYA is used to increaser the cyanuric acid, not to lower the TA. The CYA range is 30 - 50ppm. I don't know if it's a typo but the question says the CYA is 150ppm. This is much too high and will render your FC ineffective. This will be the starting point of an algae bloom. I would get that tested again and if it comes back that high the most effective remedy is a drain and refill. You can then start over with a new fill.

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

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