How Much Baking Soda to Raise Pool pH?

The pH level is a measure of how acidic or alkaline your pool water is. The pH scale ranges from 0 to 14, with 7 being neutral, numbers less than 7 being acidic, and numbers greater than 7 being alkaline. Untreated water has a pH of 7, meaning it is neither acidic or alkaline. The recommended pH of pool water is 7.4-7.6, meaning it is alkaline.

As a pool owner, you should know that keeping your pool water’s pH and alkalinity at the range of 7.4-7.6 and 80-120 ppm respectively is optimal for preventing and solving many problems. Since pool water tends to become acidic over time, you’ll find yourself adding bags of baking soda or soda ash to increase the pH and alkalinity and testing the water frequently.

Depending on how large your swimming pool is, you may find yourself adding literally dozens of pounds of baking soda, and this can make any pool owner question if perhaps they are adding too much, or if they can trust their calculation?

The question of how much baking soda is required to raise the pH is not the right question. Baking soda primarily increases alkalinity and does not increase pH much at all. For reference, to increase a 10,000 gallon pool’s pH from 7.2 to 7.6, you’d need to add a whopping 21 pounds of baking soda. This dose would increase the alkalinity by 150 ppm which is simply too much. Comparatively, using only ¾ pound of soda ash would net the same 0.4 increase in pH while only increasing alkalinity by 8.6 ppm.

In this article, we will discuss how much baking soda increases pool pH and alkalinity, the relationship between pH and alkalinity, and common mistakes beginners make when trying to balance their water chemistry.

The relationship between baking soda and soda ash

We cannot talk about baking soda (sodium bicarbonate) without also talking about soda ash (sodium carbonate). The general recommendation is that baking soda is used to increase pool alkalinity, whereas soda ash is used to increase pool pH.

However, it is impossible to increase only the pH or only the alkalinity. Whether you add baking soda or soda ash, both chemicals can increase the pH and alkalinity of the pool water. That said, there is still a best practice you should follow.

Since baking soda primarily increases alkalinity and only raises the pH of the water slightly, you would use it only if your pool’s alkalinity is low. Conversely, soda ash can increase both the pH and alkalinity greatly, so you need to be careful not to exceed either one.

Using baking soda when you should have used soda ash can result in a situation where you would need dozens of pounds of baking soda to increase the pH only slightly, but you would have increased the alkalinity by far too much.

How much of an increase in pH and alkalinity do baking soda and soda ash cause?

The rule of thumb is that 1.5 pounds of baking soda added to a 10,000 gallon pool will increase the alkalinity by 10 ppm. The goal is to keep the alkalinity at 80-120 ppm. As for the increase in pH, this is too small  an amount of baking soda to be measured by standard test kits.

Comparatively, soda ash (sodium carbonate) only requires 12.2 ounces (~0.76 pounds) to increase the pH of a 10,000 gallon pool by 0.4, as well as increase alkalinity by 8.6 ppm (these assumptions assume a starting pH of 7.2 and alkalinity of 60).

Knowing these numbers, pool owners are not recommended to add the full amount into their pool all in one go. For soda ash, you could add 6 ounces per 10,000 gallons, resulting in only a 0.2 increase in pH and a 5 ppm increase in alkalinity, allowing you to fine tune adjustments so that you don’t accidentally go over.

If you were to try to increase a 10,000 gallon pool with a pH of 7.2 to 7.6 using only baking soda, it would take nearly 21 pounds’ worth. The issue here is not just the amount of baking soda required, but also that it would drastically increase alkalinity by 150 ppm.

If your goal was to increase the pH by 0.4 while keeping the alkalinity increase to a minimum, then you can use 12.2 ounces of soda ash to do so, meanwhile total alkalinity would only go up by 8.6 ppm.

If you aren’t sure where I’m getting these numbers or how the calculations are done, don’t worry. You can use a pool calculator to help you figure out how much of which chemicals you need to add.

How come so much baking soda is required to increase pH?

Why is it that you would need dozens of pounds of baking soda just to increase the pH by 0.4? The reason is that the pH scale is not a linear scale, but rather a logarithmic scale. In other words, an increase of one whole pH number requires a tenfold increase in the amount of product needed.

To put this into perspective, increasing the pH from 7.2 to 7.4 using baking soda would require 91.9 oz or 5.75 lbs’ worth. To increase it from 7.4 to 7.6, rather than adding another 5.75 lbs’ worth, you would need 243.9 oz or 15.24 lbs of baking soda. Meanwhile, the alkalinity would be increased far above the optimal range, so you would never be adding this much baking soda in the first place.

The bottom line

If your calculations were that you needed an obscene amount of baking soda to increase your pool pH, the problem is that you’re not using the right product for the job. Soda ash would increase your pH handily without raising the alkalinity through the roof.

Furthermore, you probably didn’t want to pay for dozens of pounds of baking soda each week anyways. Since you need less soda ash to accomplish the job, it is much more economical and less of a hassle to just add 12.2 ounces (~0.76 pounds) of it to increase your pH from 7.2 to 7.6, rather than using 21 pounds of baking soda.

You also wouldn’t have to worry about the “yo-yo” effect adding baking soda causes, which requires you to add muriatic acid to decrease the alkalinity. However, adding muriatic acid would decrease the pH as well, so need to add baking soda again, which further increases the alkalinity. This yo-yo effect could last a while and is not only frustrating but a huge waste of resources.

Better to use the right chemical for the job, and to add them sparingly so that you can fine-tune the doses better. Since you now know how much baking soda, or even better, how much soda ash to add to increase the pH, then you can avoid this headache and get your desired results quickly and on a budget.