How to Lower pH in a Pool Without Chemicals (Naturally)



Looking for convenient or environmentally friendly ways to lower the pH of your swimming pool?

This article will cover how to lower pH in a pool without chemicals, through natural and organic methods, as well as how to lower pH using everyday household products.

How to Lower pH in a Pool Naturally

These are the best ways to lower pH naturally in your pool:

Raise the Temperature of the Water

The temperature of your water has a subtle effect on the pH level.

As the water gets colder, the pH naturally shifts upwards. Conversely, as the water gets warmer, the pH slowly drops.

This difference can naturally be seen during the winter and summer months, but you can also force a small pH change by intentionally heating your water.

While you can use a pool heater or heat pump to get the job done, both require plenty of gas or electricity to run. If you want a more eco-friendly option, try using a solar pool cover instead.

Technical explanation: This happens because calcium is less soluble in warmer water. When calcium falls out of solution, it drives up the LSI of the water, which forces a pH decrease to bring the LSI back to neutral.

Inject CO2 Into the Water

All pools have carbon dioxide (CO2) in their water, almost like a giant can of soda.

Since carbon dioxide is acidic, the more of it you have dissolved in your water, the lower the pH of your water is going to be.

The issue is, however, pools lose (off-gas) CO2 through lots of movement on the water surface; a process called aeration, caused by water features, saltwater generators, or simply just splashing.

This steady loss of carbon dioxide slowly increases the pH of your pool water.

One way to counter this effect is to inject carbon dioxide straight back into the water using a dedicated CO2 system. This setup often requires a continuous supply of carbon dioxide to your pool, however.

Pro tip: You can minimize CO2 off-gassing by lowering total alkalinity. Over-carbonated water off-gasses more quickly, so lowering carbonate substances (which fall under total alkalinity) reduces the rate of off-gassing.

Drain and Refill the Water

Sometimes, the most effective way to fix a pool pH problem without using chemicals is to replace the water entirely.

If your water is too basic, partially draining and topping off the pool with lower pH water will naturally bring it back down. In extreme cases, it may even be necessary to do a complete drain and fill.

Of course, if your goal is to be more green with your pool maintenance, dumping all isn’t exactly eco-friendly, either.

How to Lower pH in a Pool Using Household Products

These are the best ways to lower your pool’s pH using easily accessible household products:

Add Muriatic Acid

Muriatic acid, or hydrochloric acid, has a low pH level of between 1 and 2.

This acidic substance is commonly used as a heavy-duty cleaning agent for dealing with stains on brick and concrete, as well as removing rust.

It can also be used to lower pH and total alkalinity in swimming pools, and despite some concerns with handling and safety, it happens to be one of the most common substances for doing so.

There are two methods for adding this acid to your water:

  1. Pour it straight into the measuring cup and into the water
  2. Dilute the acid in a jug before measuring it out

Both are viable methods, but some pool owners feel safer diluting the acid before adding them to water. 

For exact measurements on how much to use, refer to this pool calculator.

Add Vinegar (Not Recommended)

Vinegar is acidic with a pH level of 2 to 3, so you can, in theory, add this to your pool to lower the pH of your water.

In reality, though, you probably shouldn’t.

While vinegar will be successful in bringing down the pH of water, it poses some issues when used in swimming pools.

First, despite being acidic, vinegar is heavily diluted and therefore not strong enough to make any real impact on the pH in your pool without adding a truckload of it. Even if you had that much vinegar to throw in, think of the smell… ugh!

Secondly, it adds other unnecessary organics (acetates) to your water. While these aren’t particularly harmful, they’re certainly not useful either.

What About Bleach?

Liquid bleach, such as Clorox, has a pH level of around 11-13.

In other words, bleach does NOT lower pH, it actually raises pH in your pool.

Unlike other high pH solutions, however, liquid bleach (or liquid chlorine) only has a temporary impact on pH because it’s offset by the acidic chemical reaction that takes as it enters the water.

In short, as the bleach gets used up, the slight pH impact on your water is essentially canceled out, making it pH neutral in the long term.

What We Recommend

Traditionally, the most efficient way to lower pH in a pool is to use muriatic acid or sodium bisulfate (dry acid).

While these are not necessarily the most eco-friendly chemicals on the planet, it’s worth keeping them in your back pocket if you’re struggling to lower pH using non-conventional methods.

Categories: Pool Care, Pool Chemistry