It sometimes feels like owning a pool requires you to be a chemist in your free time. There are so many tests to perform, and all kinds of measurements to track.
The good news is, baking soda is a simple, safe way to help maintain water quality in your pool, keeping your water clear, sparkling, and pleasant to swim in, without drying the skin or stinging the eyes.
But how exactly does it work? And how can you use baking soda to improve the water quality in your pool? Today, I’ll tell you all about it.
You may have heard rumors that you can clean your pool by just adding baking soda, and it seems like such a simple, easy solution. But is it true?
While a baking soda scrub is a great way to clean pool tiles, grout, and furniture, baking soda doesn’t really “clean” a pool. Instead, baking soda helps to maintain the pH levels of the water, which keeps a pool healthy and inviting.
One of the most important ways to maintain a pool is to measure and maintain the right pH levels. If the pH levels are low, it means the water has become acidic.
Acidic water is bad for the pool itself, because it may corrode pool tiles and fixtures. And acidic water can be uncomfortable for swimmers, drying out the skin and hair.
Over time, the water in a pool naturally tends to become more acidic. Rain has a pH of 4-5, so rain water can affect the pH of a pool. Body fluids, chlorine, and organic debris can also lower the pH level of a pool, so that’s why the pH level needs to be measured fairly often: it changes over time.
Because pool water tends to become more acidic over time, adding alkalizing agents preserves a safe, comfortable, stable pH level in your pool water. Alkalinity is a measure of how much acid your water can absorb or buffer by absorbing hydrogen to create neutral bicarbonate ions.
In other words, pH levels are a snapshot of the acid levels in your pool right now, while alkalinity is a measure of your pool’s ability to neutralize acid in the future.
Ideally, a pool should have a pH level of about 7.2 – 7.8. On the pH scale, 7 is neutral, so you want the water to be slightly alkaline.
When your pool water is too acidic, it can be corrosive and irritating, a bit like an acid reflex in an upset stomach. In the same way that baking soda can calm acids in the body, and you take it for heartburn, baking soda can also calm the acids in a pool and restore them to comfortable neutrality.
Baking soda can work wonders in a pool. Baking soda can:
- Help to clear cloudy water and restore sparkle
- Spot-treat algae
- Make the pool water softer on your skin
- Prevent corrosion and damage to pool equipment
- Complement the effectiveness of chlorine
Baking soda has a pH of 8.3, and the bicarbonate ions in baking soda act as a pH buffer. They have a negatively charged end, and a positively charged end. When either positive or negative ions attach to these ends, they form a compound that becomes solid and settles out of the water. It’s called a “buffer” because, with its positive and negative ends, it can either raise pH to 8.3, or lower pH to 8.3. In other words, it can act as either an acid or a base, depending on the environment it’s in, which makes it a great way to stabilize water and “buffer” it from rapid changes.
Chlorine can clean a pool even when the pH is low and the water is too acidic, but you’ll get far more mileage from your chlorine when the pH is slightly alkaline.
However, even when the chlorine is working and at the right levels, a pool can still have cloudy water, or be uncomfortable to swim in. And acidic water often has too much chloramine in it, which stings the eyes and produces that “pool smell”.
In other words, to have a healthy pool, you need to maintain the right levels of chlorine, and the right level of pH. Those two values work together, but aren’t the same thing.
When you read about people dumping pounds of baking soda into a pool, it’s natural to wonder if there are any risks to the water quality, pool equipment, or health of the pool. But baking soda is safe and natural. It has an extremely low risk of being harmful to people or to a pool, which is why so many people use it to adjust their pH and alkalinity levels.
If you add too little, it simply won’t be effective and your levels will remain too low. If you add too much, raising your pH too far outside of the desired range, particularly if you have hard water, it can cause calcium to start to build up in your pool. Too much calcium can make the water cloudy, build up a scale on pool surfaces, and clog your filters.
Because pool water naturally tends toward becoming more acidic over time, the water usually only becomes too alkaline when people have adjusted it incorrectly. That’s why you should add the right amount of baking soda, stir it to dissolve, and then test again the next day to see if further adjustments are needed.
Here’s how to use baking soda in your pool:
- Step 1: Test your pool’s water for your pH levels and also for total alkalinity. If your pH is below 7.2, and your total alkalinity is below 80ppm, then you need to add baking soda.
- Step 2: Determine how much baking soda you need. This part calls for some math. As a rule, 1.25 pounds of baking soda will raise the pH level of a 10,000 gallon pool by 10ppm. Since you want your total alkalinity to measure 100ppm, you can figure out how much baking soda you need based on your total alkalinity and the volume of your pool.
- Step 3: Get your baking soda. Since you will probably need several pounds of baking soda, you won’t be able to simply pick up a box at the grocery store. Instead, you may need to get a big bag at a pool supplier or order it online.
- Step 4: Add the baking soda to your pool. Don’t add more than 2.5 pounds of baking soda in a single day. Start by adding 1.25 pounds (or the minimum amount you need to raise the alkalinity by 10ppm). Sprinkle the baking soda over the surface, or pour it into a skimmer, using a circular motion that helps it dissolve more quickly. Keep the pool water in motion to avoid cloudiness.
- Step 5: Allow the baking soda to circulate. Depending on the size of your pool, it may take 6-10 hours before the water is fully circulated.
- Step 6: Re-test your water and repeat adding baking soda if necessary.
Baking soda is also a great way to spot-treat algae problems in a pool. If you have black or brown algae spots in a pool, here’s how to use baking soda to treat them:
- Step 1: Use an algae product. Get an algae killing product and add it to the pool, following the manufacturer’s instructions.
- Step 2: Allow the product to circulate. Depending on the size of your pool, this could take 6-10 hours.
- Step 3: Sprinkle baking soda in the problem area.
- Step 4: Use a pool brush to scrub the area
Some people recommend using baking soda (sodium bicarbonate) to adjust both pH and total alkalinity levels.
However, sometimes you may have a pool with the proper alkalinity levels, but a low pH. In that case, it’s more effective to use soda ash (sodium carbonate). Soda ash can also be used in much smaller amounts, to adjust only the pH without the total alkalinity.
- Adjusting the pH level in a 10,000 gallon pool from 7.2 to 7.6 would require 21 pounds of baking soda. That would, unfortunately, increase the total alkalinity to nearly 150ppm, far more than is good for a pool.
- Adjusting the pH level in a 10,000 gallon pool from 7.2 to 7.6 takes only 12.2 ounces of soda ash, and adds less than 10ppm to the total alkalinity.
The pH level of baking soda is 8.3, so it takes a lot of it to raise a pool’s overall pH level. The upside is that using baking soda will never make a pool’s pH level higher than 8.3 (and if the pool’s pH level is higher, baking soda will lower it), but it’s better at adjusting the overall alkalinity of the water.
The pH level of soda ash is 11.4. This means it takes very little of it to adjust the pH levels, but it isn’t great at adjusting the overall alkalinity.
In other words, while you can use baking soda to adjust the pH level of a pool, it’s better to use it to adjust overall alkalinity. If you need to adjust only the pH level, with lessened impact on overall alkalinity, it’s better to use soda ash.
Baking soda is a simple, safe, effective way to help your pool stay clean, and keep the water clear and comfortable for swimmers.
But also consider soda ash for a more aggressive treatment; both products offer different ways of controlling a pool’s pH levels and maintaining your water quality.