How to Lower pH In Your Pool: 8 Step Guide

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Need to lower your swimming pool pH? Our easy how-to guide shows you what to do.

If you’ve got a problem with the pH level in your pool you’ll know this can be very frustrating.

When your pH level gets too high it will start to affect everything else in your pool. It could make the chlorine, the chemical that keeps your pool clean, a lot less effective. That means the water could be unsafe to swim in.

The good news is there are ways to fix it. We’ll run through the solutions in this 8-step guide to a lower pool pH.

How to Lower pH In Your Pool

What is my pool pH?

The pH scale measures whether something is acid or alkaline. The scale ranges from 0 to 14, with 7 being neutral. Pure water has a pH of 7.

In your swimming pool you are looking for an ideal pH of around 7.4 (between 7.2 and 7.6 is just fine).  You can get pH kits to find out where your pool is on the scale.

The lower the pH number, the more acidic the water in your pool is. The higher the number, the more alkaline the water is. You might remember this from school – did you ever do the litmus test? Red was acid, blue was alkaline.

Why is it important to get the pool pH right?

How to Lower pH In Your Pool

If the water in your pool is too acidic it will corrode equipment and surfaces. It will also irritate your skin and eyes.

But if the water in your swimming pool is too alkaline you will end up with a cloudy pool – and just like a build-up of limescale in a kettle, you could get scaling in your pool too.

Is a pool pH problem serious?

A swimming pool with a pH that isn’t correctly balanced is a problem for various reasons.

For a start it can cause serious health concerns. A lower pool pH could kill off the benefits of chlorine, making your water potentially unsafe to be in.

Chlorine kills off the causes of various diseases and conditions including ear infections, athlete’s foot, and Legionnaires’ disease. So it’s important to get the chlorine level right in your pool.

Besides the health issues, an unbalanced pH level in your pool could damage your equipment. If you have water that is too alkaline you could see pipes and filters clogged with scaling.

This could end up being a pricy problem if you allow it to build up. Your pump will still be trying to force the same amount of water through clogged up pipes. It’s easy to see how this could end up wearing out your equipment.

What causes a high or low pH level?

How to Lower pH In Your Pool

Don’t worry if you get the occasional reading outside of the ideal range – this is bound to happen sometimes. But if you are constantly trying to keep your pool pH within range you will need to take some action.

The pH of the pool water is affected by everything that enters the water – so it’s not always that easy to keep it under control.

Two possible reasons why your pH level is too high:

  • The wrong amounts of chemicals. Have you recently added chemicals to raise the pH? You might have added too much and sent the pool pH to the alkaline end of the scale.
  • Pool shock. If you’re using calcium hypochlorite, it can raise the pH levels in your pool. Shocking your pool is good, but check you are using the correct levels of chemicals.

So how do you lower the pH in your pool? Read our step-by-step guide.

Your 8 step guide to lower pool pH

Lower pool pH effectively with our step-by-step guide.

  1. Buy a pH-lowering chemical. Sodium bisulfate and muriatic acid are both used to lower pool pH. You’ll often find them sold under names such as ‘pH Minus’ or ‘pH Down’, or they may be called pH reducers. Sodium bisulfate is a milder chemical than muriatic acid (muriatic acid is also known as hydrochloric acid), so it is often the preferred choice. Care should be taken with both.
  2. Choose a calm day with no wind. You want to get the chemicals in the pool, not blowing away in the wind. Sodium bisulfate is a powder (also known as dry acid) so this could be a problem on a windy day. Even with liquid chemicals it’s safest to choose a calm day with no wind. Muriatic acid is strong stuff used for extreme calcium build up and needs extra care.
  3. Check your pool pH and alkaline levels before you start. As we said above, pH should be between 7.2-7.6. Alkalinity should be between 80-120ppm. If you are getting high readings, it’s time to start lowering them.
  4. Wear the right clothes. These chemicals can damage skin and pool surfaces. Wear clothing that covers all of your skin, plus goggles and rubber gloves.
  5. Measure the chemical out. Use three-quarters of the recommended amount to start with. Read the manufacturer’s instructions and make sure you get this right. It’s a good idea to err on the side of caution. It will be easier to add more later, but not so easy to take it away!
  6. Add the chemical to your pool. If you are using sodium bisulfate pour the powder into the return jet sites where the water comes into the pool. Avoid getting it in the skimmer. If your pool is above ground you’ll need to manually circulate the water to spread the chemical around in the pool.

    If you are using muriatic acid there are a couple of ways to add the liquid. Turn your pump off and pour a slow steady stream into the deep end. This will make sure it’s not just floating around on the surface. Then turn the pump back on and let it circulate. Or you can add the liquid to the return jet sites as described above for sodium bisulfate.

    If you need to move the muriatic acid around with your hands in the water you must make sure you wear rubber gloves. Pour small amounts in different areas of the pool to avoid too much being concentrated in one spot, and stir the water around wearing your rubber gloves.
  7. Allow the chemical to dissolve for 15 minutes. Your filtration system will circulate it around the pool.
  8. Test your pool pH again. It’s a good idea to do this within 4 hours, and definitely within 24 hours of adding the chemical. If you need to lower the pool pH further, add some more of the chemical by repeating the steps above until it’s back between 7.2-7.6.

How to keep the pH levels in your pool just right

As we said above, keeping your pool’s pH level within range can be a tricky business. If it’s a regular problem, think about what you might need to change in your pool maintenance regime. Here are some regular checks you can carry out to improve the water in your pool.

  • Clean your pool. If you get lots of leaves and other debris in the pool it could affect the pH. It doesn’t take long and it’s a good idea to do it every day if you can.
  • Test the water regularly. It’s worth testing more often if you have a problem with your pool pH – every day until you get the levels within range.
  • Check the filters are working properly. Your filtration system should be helping you to keep your pool water clean – make sure it’s working.
  • Shock your pool once a month. If you’ve never heard of this it will help with pH levels a lot. Basically it resets your pool chemistry to normal.
How to Lower pH In Your Pool

Got the pH sorted? Now test the whole pool

Once you have got your pH level stable it’s a good idea to test the pool’s chlorine levels to make sure that’s ok too. As we said above, chlorine cleans your pool by destroying bacteria and other nasties that spread diseases, so it’s important to get it right.

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