Maintaining the appropriate pH level in a swimming pool is crucial to ensure the health and safety of swimmers, and to prevent damage to pool equipment and the pool structure itself.
When the pH level in a pool becomes too high, it can lead to problems such as skin irritation, cloudy pool water, and decreased effectiveness of sanitizing chemicals.
In this article, we will discuss how to lower pH in pool water, including the use of muriatic acid and dry acid.
Why is my pH so high?
Several factors can contribute to high pH levels in a swimming pool.
- One common cause is the use of hard water to fill the pool. Hard water contains high levels of calcium and magnesium, which can cause the pH level to rise over time.
- Another possible cause is the use of certain pool chemicals, such as algaecides and clarifiers, which can affect the pH balance.
- This can be particularly true when using liquid chlorine to increase the chlorine levels in a pool or to shock it. This is because liquid chlorine can have a pH of 13 which will increase the overall pH of your pool.
Testing the pH level of your pool
First and foremost, it’s important to test the pH level of your pool regularly using a reliable testing kit (click on the image above to check out the Aquachek test strips I use)
Without testing, you would never know whether you need to lower your pool’s pH or not.
A pH level of 7.2 to 7.8 is considered optimal for most pools. If your test results show that the pH level is higher than 7.8, it’s time to take action.
Recommended Test Strips
Aquachek 7-way test strips
These are the test strips I use, that can tell you the total chlorine/bromine, free chlorine, pH, total alkalinity, CYA and hardness levels.
How to lower pH in pool
What lowers pH in a pool? Well the answer is using an acid. Generally when lowering pH in pool water you would use either Muriatic acid or dry acid.
That may sound rather dangerous but by taking some sensible precautions it is perfectly safe.
Using Muriatic Acid to lower high pH
One of the most effective and common ways to lower high pH in pool is to use muriatic acid. This is a strong acid that should be handled with caution.
Before adding muriatic acid to your pool, be sure to wear protective gloves and eyewear, and follow the manufacturer’s instructions carefully on how to bring ph down in pool. It’s important to add the acid to the water slowly and in small amounts, while constantly monitoring the pH level.
You should follow the manufacturer’s instructions when adding Muriatic Acid or you can use the guide below to work out approximately how much acid to add.
| pH Level | Muriatic Acid (ounces) |
|---|---|
| 8 | 5 – 8 ounces |
| 9 | 10 – 16 ounces |
| 10 | 16 – 24 ounces |
| 11 | 24 – 32 ounces |
| 12 | 32 – 40 ounces |
| 13 | 40 – 48 ounces |
| 14 | 48 – 56 ounces |
Be aware that adding too much muriatic acid can cause the pH level to drop too low, which can be just as problematic as a high pH level. You may then end up chasing your tail – adding baking soda or soda ash to raise the pH and end up with more of a chemical soup rather than pool water!
Steps to add muriatic acid to your pool:
- Test your pool’s chemical levels with a liquid or strip pool testing kit.
- Wear protective gear that comes to your arms and legs to avoid acid burns on the skin, as well as goggles to prevent droplets in the eyes.
- Dilute the acid before dumping it into the water to allow the right chemistry to be reached. Always dilute it by filling a bucket with water first and then add the chemical – never add the chemical first. Don’t pour the acid directly into the water without diluting it first as it could cause a harmful, chemical reaction.
- Walk around the pool slowly pouring in the diluted acid to distribute it evenly.
- Leave your pool pump running to circulate the water.
Caution: If you have a vinyl-lined pool you should consider using dry acid as Muriatic Acid could affect the liner, particularly if you have a patterned liner.
You can find out how to add muriatic acid in this article.
Using Dry Acid for pool pH decrease
Another option for lowering the pH level in a pool is to use dry acid. This is sodium bisulfate and is often sold as pH Reducer, pH Down or sometimes pH Minus.
This is a safer alternative to muriatic acid, but it can take longer to achieve the desired pH level. Dry acid is available in granular form and can be added directly to the pool water, although personally, I would always dissolve it in a bucket of water first.
As with muriatic acid, it’s important to add dry acid slowly and in small amounts while monitoring the pH level. Ideally, leave it a few hours with the pool pump running between tests.
For every 10,000 gallons of pool water, to lower the pH from 8.5 to 7.5, you would need to add approximately 600g (21 ounces) of sodium bisulfate (assuming a concentration of 92%).
Do not add more than 150g (5 ounces) of sodium bisulfate per 2,500 gallons of pool water at any one time.
Steps to add sodium bisulfate to lower pool pH:
- Test your pool’s chemical levels with a liquid or strip pool testing kit.
- Depending on the pH level and how much is needed to reduce it, some experts recommend ¾ of what the instructions call for. You can always add extra later.
- Read the label to determine whether the product needs to be diluted.
- Walk around the pool slowly pouring in the sodium bisulfate to distribute it evenly.
- Leave your pool pump running to circulate the water.
- After the water rests for six hours, retest and add more if necessary.
How to maintain a healthy pH level in your pool
In addition to using acid to lower the high pH in the pool, there are a few other steps you can take to help maintain a healthy pH level.
You can also limit the use of liquid chlorine, which can contribute to high pH levels, or consider using alternative sanitizing methods such as saltwater systems.
Provided your city or well water is not high in calcium you could partially drain and refill the pool.
You can limit the amount of time swimmers spend in the pool, as well as the number of swimmers in the pool at any given time. This is not an easy option and almost defeats to object of having a pool.
How can I lower the pH in my pool fast?
Using pH reducer (aka pH minus, sodium bisulfate and dry acid) will help to reduce the pH levels in your pool quite quickly.
Can you use vinegar lower pool pH?
Although in theory, you could use vinegar it is actually a very weak acid so you would need to use a great deal of it to have any effect on the pH. It also stinks (in my opinion) so would you want to come out of your pool smelling like a pickle?
How do I reduce the pH in my pool naturally?
Patience is generally the answer. Over time the pH may well come down on its own along with regular cleaning.
Does chlorine raise or lower pH?
Chlorine will not lower the pH in a pool. If using liquid chlorine, which has a pH of 13, the pH is likely to go up however the extent it will raise it will depend on how much you add.
In conclusion
if you notice that the pH level in your pool is too high, it’s important to take action to correct the problem.
By testing the water regularly, using muriatic acid or dry acid as needed, and taking other preventative measures, you can help ensure a safe and enjoyable swimming experience for everyone.
I have had hot tubs for over 20 years and a pool for the last 10 years. I had to learn how to clean, maintain and fix them the hard way. Since then I have helped many friends and neighbors with their pools and now I want to share everything I have learned with you. About Me
