The Best Ways to Raise or Lower pH and Alkalinity in Pool or Spa Water

Has your pool water gone cloudy? Or perhaps you’ve noticed some scaling building up on the sides of the spa?

This could indicate that the water’s pH level is not what it should be.

While pool chemistry can be a tricky thing to master, we at Sutro want to help you simplify the process.

That’s why we’ve written this article to let you know how to raise pH in a pool as well as how to lower pH in a pool.

This also applies to a spa as well.

What is pH and what should it be?

pH simply means the water’s total acid-alkalinity balance.

Pool experts suggest that the ideal pH reading of pool or spa water needs to be between 7.2 – 7.8.

If the balance is off, problems can and probably will occur in your pool or spa.

Any element added to the water, be it sweat, sunscreen or leaves or bugs will cause the pH to change.

If the water becomes too alkaline (between 7.8 – 10), the water can become cloudy or it can cause scaling on the plumbing equipment and on the pool lining; something that can be costly to fix.

If the water is too acidic (between 1 – 6.9), it can cause etching or corrode the metallic equipment. In the worst-case scenario, highly-acidic water can give you and your guests skin rashes or irritations.

For these reasons, it’s important to monitor pH levels closely. 

It’s also important to note that the water will need to be tested more frequently during periods of high usage due to an increase in by-products from swimmers (sunscreen and natural oils from hair and bodies) or simply from dirt that gets tracked into the pool. 

What’s the Difference Between pH and Alkalinity? 

While alkalinity and pH are pretty similar, knowing the difference can make all the difference to your pool’s health.

As mentioned above, pH is how acidic or alkaline the water is and is tested on a scale from 1-14.

Alkalinity, on the other hand, is the absolute measure of the concentration of all alkaline substances in the water and is measured in parts per million (ppm). 

The recommended level of total alkalinity of a pool should be 80-120 ppm. 

Check out our article about the basics of pool chemistry, when you want to learn more.

How to Lower pH in Pool Water

Lowering the pool’s pH can be done in a number of ways using a variety of pool water products. The first one we recommend is muriatic acid,  also known as hydrochloric acid, which is especially useful for larger pools.

Make sure to purchase one that is meant for swimming pools or spas to get the correct concentration level.

Read the instructions carefully, as some muriatic acids are pre-diluted and can be added to the pool directly.

Others may need mixing in a bucket of water before putting it into the pool.

Remember, always mix chemicals into the water, not the other way around, as you want to avoid the concentrated acid getting splashed up if the water is added. 

How much you need to add will depend on the size of your pool, as well as its current pH level.

As with all pool chemicals, be sure to wear protective clothing in case of spills. 

Another product you can use to decrease the pH of the water is sodium bisulfate, also known as dry acid. This acid has the advantage of being easier to handle than muriatic acid. Follow the instructions carefully as different manufacturers have different instructions.

With both of these products, make sure to add them in front of the return jets and wait 4 hours before anyone gets in to ensure that the acid has circulated evenly throughout the water. 

How to Raise pH in Pool Water

If it is too low, add soda ash to raise the pH level in your pool. Soda ash is also known as sodium carbonate or pH Up.

We recommend never adding more than 2 lbs or 900g of soda ash per 10,000 gallons of water per treatment.

Calculate how many gallons your pool has with our pool volume calculator.

Starting at the deep end, sprinkle the soda ash over the entire surface of the pool.

Make sure that the pump is circulating to move the water around and then wait at least an hour before testing your water again.

If the pH is still too low, try adding some more soda ash. Soda ash may make the pool water a little cloudy at first, but it should become clearer after a day or so. 

How to Lower Alkalinity in a Pool

If the alkalinity of the water is too high, i.e. more than 120 ppm, it’s an easy fix to lower the alkalinity of the water:

First, make sure the water pump is on and take a current pH measurement. 

Add one quart (946ml) of muriatic acid or 2 pounds (0.9kg) of dry acid at a time around the perimeter of the pool.

Let the acid mix in the water for about an hour, then test the water again. Maintain a water pH of about 7 and keep adding pool acid in small increments until the correct alkalinity level is reached.

Once the alkalinity level is correct, allow the pH to climb naturally by circulating the water.

Only add soda ash to raise the pH if the pH stops climbing after 1 week.

Sodium bicarbonate- an Alkaline Booster

An easy and safe way to give your pool an alkalinity boost is to use sodium bicarbonate.

When you need to raise the pH, you can add sodium bicarbonate, but only if the total alkalinity of the water is also low.

Balance is Important for pH

While testing and maintaining the pH balance of your pool or spa water is a constant process, hopefully, the tips in this article will help you take some of the pain out doing so.

When you need help monitoring your pool water the Sutro pool ph monitor is the solution.

The raising and lowering the pH in your pool will be something that you will always need to balance.

The ways to lower and raise pH are many and if you have any questions, it’s best to talk to a pool professional.

That way, you’ll know what to do when your pH is either too high or too low.

Have questions? Let us know or check other pool maintenance tips!

What about Hot Tubs and Spas?

Hot tubs and spas also require a careful balance of these chemicals in order to function properly. Too much or too little of any one chemical can cause problems with the hot tub or spa. We’ve created a thorough article to understand more all you need to know about hot tub chemicals.