Is the pH level in your pool too low?
Are you looking for the easiest, fastest, and most efficient way to raise the pH in your pool?
This article will explain multiple chemicals you can use to lower your pH level, how to choose the right method, and how to prevent or slow the rising pH in your pool.
When is pH too Low?
pH measures how acidic or basic your pool water is.
This is measured on a scale of 1 to 14, with 7 being neutral. Anything below 7 is increasingly acidic and anything above 7 is increasingly basic.
When your water becomes too acidic for too long, some pretty undesirable things start to happen. These include etching of your pool surfaces, corrosion of your pool parts, and general discomfort to swimmers.
Ideally, you want your pH level to stay between 7.2 and 7.8 (slightly basic).
While a temporary drop below 7.2 shouldn’t be cause for concern, it’s important to take steps to bring it back into range as soon as possible, especially with drastic drops in pH.
What Product Should You Use to Raise pH?
The chemical products most commonly used to raise pH in swimming pools are either baking soda, soda ash, or borax.
Any product used to raise the pH level will also raise the total alkalinity to varying degrees:
- Baking soda raises pH a tiny amount while raising alkalinity a lot
- Soda ash raises pH while also raising alkalinity
- Borax raises pH a lot while only raising alkalinity a little
Which product you should use depends on your total alkalinity at the time of raising your pH, as you always want to keep alkalinity between 80 and 120 parts per million (ppm).
To give you a practical example:
- If your alkalinity is 100ppm, you would be better off using borax to increase pH as you can only afford a small increase in alkalinity.
- If your alkalinity is only 50ppm, you would be better off using soda ash to significantly increase both at the same time.
Note: If you’re looking to raise pH without raising alkalinity at all, see the next section on using a natural process called “aeration”.
How to Raise pH In a Pool (Fastest Method)
Follow these step-by-step instructions:
1. Test Your Pool Water
Whenever you’re adjusting anything in your pool, it’s important to take a last-minute reading to know exactly where you stand.
Since you’re going to be adding a pH increaser to your water (which also raises alkalinity to some degree), you’ll need to know your pH level and total alkalinity.
The ideal ranges for both are as follows:
- pH level between 7.2 and 7.8
- Total alkalinity between 80 and 120pppm
While you can use test strips for this, a liquid test kit will give you a more accurate reading. Alternatively, you can use an in-store testing service but these will be no more accurate than what you can do at home.
2. Pick Your pH Increaser
Now that you have a handle on your pH and alkalinity, you can make an informed decision about which chemical to use.
Remember, when raising pH using chemicals, you need to be mindful of how much you’re going to raise your total alkalinity in the process (this is unavoidable).
As a rough guide:
- If you have low(ish) pH and very low alkalinity, use baking soda.
- If you have low pH and low alkalinity, use soda ash.
- If you have low pH and low(ish) alkalinity, use borax.
Note: If your alkalinity is already on the high side, the only way to raise pH without also raising alkalinity is to use aeration (see next section).
We’ll talk about exact measurements soon enough, but first, you need to know how much water your pool holds.
3. Calculate Your Pool Volume
If you don’t know your pool volume, you’ll need to figure that out next.
Don’t worry, this is easily done by plugging some measurements into your calculator. Just follow our instructions below.
For rectangular or square pools:
- Measure the length, width, and average depth of your pool (in feet)
- Multiply the length by the width, then multiply that by the depth
- Take the number you end up with and multiply that by 7.5
For round pools:
- Measure the diameter of your pool (in feet)
- Multiply the diameter by itself (diameter x diameter)
- Take the number you end up with and multiply that by 5.9
The resulting number is your pool volume (in gallons).
Note: If you prefer to use an online calculator instead of doing these sums yourself, use this pool volume calculator.
4. Measure Out Your pH Increaser Dosage
You now have all the numbers you need to determine the correct amount of baking soda, soda ash, or borax to add to your pool water.
As a general rule of thumb, per 10,000 gallons:
- 27 oz of baking soda raises pH by 0.02 and alkalinity by 10ppm
- 6 oz. of soda ash raises pH by 0.1 and alkalinity by 3.5ppm
- 11 oz. of borax raises pH by 0.1 and alkalinity by 1.8ppm
We can’t provide specific numbers for these increases because it depends on your relative pH and alkalinity, but you can plug your numbers into this pool chemistry calculator for the most accurate suggestion.
To use the calculator:
- Enter your pool size (at the top)
- Enter your current pH level in the pH section
- Set your target pH level to a value between 7.2 and 7.8
- Enter your current total alkalinity in the TA section
- Set your target alkalinity to a value between 80 and 120ppm
- Note the dosage instructions in the pH section
5. Add the Chemical To Your Pool
Adding baking soda, soda ash, or borax to your pool water is pretty straightforward.
While some pool owners prefer to dissolve the powder in a bucket before adding it to their pool, this isn’t actually necessary.
Instead, simply add baking soda, soda ash, or borax to the water near an active return jet, or add it directly to your skimmer. This will give it enough circulation to dissolve on its own while your pump is running.
It’s a good idea to only add around 75% of the total dose and restest before adding the rest, just to prevent accidentally adding too much.
6. Retest Your Water
Leave your pump running for up to an hour to allow the powder to fully dissolve, and for water to absorb the changes.
Once enough time has passed, restest the pool water using your test strips or liquid testing kit to gauge the change in pH and alkalinity.
If you used the 75% method and your pH is still too low, go ahead and add that last 25% and repeat the process until you get your pH back up to where it needs to be.
How to Raise pH In a Pool (Natural Method)
If your pH level is low but your alkalinity is already balanced, chemicals like soda ash or borax are going to work against you.
Instead, you need to way to raise pH in isolation, which can only be done by utilizing a naturally occurring process.
That process is called aeration.
Anything that disturbs your pool water causes aeration. This includes your pump, your return jets, people splashing around in your pool, natural elements like wind and rain, and even your water features.
The more you aerate your water, the faster the pH will rise.
Technical explanation: When water is exposed to air, it causes it to lose carbon dioxide faster (like leaving a soda bottle open). Since dissolved carbon dioxide is acidic, removing it from the water raises the pH level.
While aeration happens naturally in a pool—which is why pH tends to drift upwards in most pools—you can speed up this process by adding more turbulence to the water over an extended period of time.
For example, you could:
- Run your pool pump longer
- Keep your water features running longer
- Point your return jets upwards (to bubble the surface)
- Get lots of people in the pool to splash around
- Build a DIY aerator ()
This is, however, a much slower process than simply throwing household chemicals into your pool.
In fact, depending on your starting pH level and total alkalinity, this process can take as long as several days to substantially raise the pH if you aren’t using multiple methods of aeration in combination.
Why Is Low pH Bad News?
With pH being such an integral part of your pool chemistry, you can expect some nasty side effects at both high and low pH levels.
Here’s what happens when your water becomes too acidic (low pH):
- It makes your chlorine inefficient. Chlorine burns up much faster at lower pH levels which means you have to keep adding more or risk leaving your water vulnerable to contaminants.
- It’s corrosive to metal components. Acidic water is corrosive to metal, meaning low pH can damage metal pool components like filters, heaters, and even fixtures like ladders and handrails if sustained for too long.
- It damages your pool surfaces. Low pH water will burn into plaster, tile, or concrete surfaces, leaving unsightly stains (known as “etching”). It can also cause vinyl liners to wrinkle and become brittle.
- It causes discomfort to swimmers. While this is mostly felt at extremely low pH levels, swimmers will start to experience stinging eyes, dry skin, and hair, and possibly even itching.
Note: The severity of these effects depends on other factors besides pH level. In particular, the LSI of your water plays an important role – which includes calcium hardness and total alkalinity.
Why Your pH is Low (And How to Prevent It)
The pH of your pool water is a finicky thing and there are a whole host of little things that will throw it off.
- Local water. The pH of the water you use to fill up your pool may be more on the acidic side and may contribute to a low pH.
- Storms. Rainwater is naturally acidic and an especially big storm can cause serious drops in your pH, sometimes overnight.
- Swimmers. Body oils, lotions, saliva, urine, deodorants, and any other products that swimmers might transfer into the water can significantly affect pH balance.
- Pool chemicals. You may have recently shocked your pool or added a sanitizer (chlorine and bromine are both very acidic), which can all contribute to a lowered pH.
Pick Your Poison
A low pH level makes maintaining a pool harder than it needs to be, so getting it back up into range should be your top priority.
Fortunately, all it takes is a bit of testing, some simple mathematics, and the right household product to keep your pool sparkling, clean, and perfectly balanced for the season.