How To Lower pH in Your Pool Naturally: The Complete Guide

Pool owners often think of lowering the pH as a poor decision. Acidity can corrode any pool surface, deteriorate the equipment, and make the remaining chemicals less effective.

However, a high pH can cause similar problems. If your pool’s pH is too high and you don’t want to use harsh chemicals, you’re in the right place.

To lower the pH in your pool naturally, try these tips:

1. Add lemon juice to the pool
2. Consider the pool’s water source
3. Let rainwater into the pool
4. Add Carbon Dioxide to the water
5. Remove leftover debris
6. Get rid of algae blooms
7. Put distilled water into the pool
8. Remove the calcium buildup
9. Use white vinegar (or ACV)

In this article, I’ll explain several methods to reduce your pool’s pH without using muriatic acid, dry acid, and other chemicals. I’ll also cover why the debris, rainwater, and other natural elements influence the pool’s pH and alkalinity. Let’s get started!

1. Add Lemon Juice to the Pool

Lemon juice is naturally very acidic. In fact, it’s one of the most acidic fruits you can grow. I suggest lowering your pH with a little bit of lemon juice.

You can reduce the pH without adding harsh chemicals that could cause irritation and itchiness. Adding lemon juice instead of traditional pH decreasers also lets you swim right away.

Keep these tips in mind before adding lemon juice into your pool, though:

• Too much lemon juice can add phosphates to the swimming pool. Algae loves phosphates, so it’s important to maintain your pool’s chlorine levels between 4ppm to 5ppm if you add citrus to the pool. Chlorine will prevent algae blooms, allowing the lemon juice to lower the pH.
• Many pool chemicals contain citrus because it gets rid of stains. You can remove black algae by scrubbing a lemon with it. The acidity found in lemons counteracts most algae blooms, but it’s not quite enough to fend off a massive attack. I recommend avoiding other citrus treatments while using lemon juice in the pool.
• Never add more than a gallon of lemon juice at a time. It’s best to add one gallon of lemon juice per 10,000 gallons of water, then wait for 24 hours. Test the pH the following day to determine if you need to make additional adjustments. Your pool’s pH can take several hours to show any changes.
• Circulate the pool water until the lemon juice is thoroughly mixed. Concentrated lemon juice can cause stains, corrosions, and many other problems. Its incredibly low pH is quite harmful if it’s not circulated through the pump, filter, and the whole swimming pool.

2. Consider the Pool’s Water Source

Not all water sources are equal. Some cities have acidic water, while others offer high-pH water. On the other hand, well water’s pH depends on the water below the ground.

I’ve always recommended that customers test their water source beforehand. You should check its pH, chlorine, alkalinity, and hardness.

Most water sources have a high pH. You have to add water above the skimmer basket after it evaporates to prevent air from getting into the system. The added water will often dilute the acid in the pool, increasing its pH and alkalinity.

Fortunately, lowering the pool’s pH will also drop the alkalinity, so you’ll knock both issues out with the lemon juice (and other tips in this post).

3. Let Rainwater into the Pool

Rainwater is usually acidic. You’ve probably heard of acid rain causing corrosion, but even the most gentle, level-pH rainstorms can affect your swimming pool.

Rainwater often lowers the pH and alkalinity, so it’s the perfect natural solution for those who live in rainy regions. However, too much rain can have adverse effects.

Here’s what you should know about adding rainwater to the pool:

• Rain will inevitably bring phosphates into the water. Phosphates are one of the algae’s primary food sources. Natural Chemistry Phosfree comes in a two-pack that gets rid of the phosphates in your pool. This natural solution doesn’t use harsh chemicals and is perfectly safe for immediate swimming.

• It’s impossible to know how much the rain will reduce your pool’s pH. Some rain is highly acidic, while other rainstorms hardly change the pH. However, it’s a natural solution that doesn’t require chemical intervention. You can also collect rainwater in a barrel for further use if you don’t need it right away.
• Make sure the rain doesn’t flood your pool, or you’ll have a bigger mess on your hands. Flooding swimming pools bring debris, algae, and air bubbles into the plumbing. You’ll also have to deal with muddy grass and potential rusting around the edges of the pool.

Pro-tip: I don’t suggest letting rain get into your swimming pool if there’s a lot of wind. It can bring leaves, dirt, and pollen into the pool. These contaminants cause algae blooms that take a while to deal with. However, a gentle summertime rainstorm isn’t going to ruin your pool if you have the chemistry balanced.

4. Add Carbon Dioxide to the Water

Carbon dioxide reduces the pH of your swimming pool. You can aerate your pool to increase its pH with water features or incorporate CO2 equipment into the plumbing for the opposite effect.

I suggest installing a CO2 tank into the equipment pad or hiring a professional to fill the water with CO2 to drop the pH.

Adding too much CO2 will make the pool’s pH hard to manage. It can lower it drastically, so it’s important to ask an expert how much you should add to the water. They can also install an automatic gauge that adjusts the pH when necessary.

These CO2 tanks are especially useful for new gunite pools and replastered pools with constantly-raising pH levels.

Carbon dioxide pool equipment is few and far between due to regulations and unfamiliarity. People aren’t used to bumping CO2 and other gasses (including natural chlorine gas) into their swimming pools.

Make sure you’re legally permitted to install a CO2 meter into the equipment pad before hiring a pro or DIYing the project.

5. Remove Leftover Debris

All of the debris that gets into your pool will affect its pH. Dirt, leaves, and pollen often have a low pH that will make the pool acidic.

However, some debris is basic and can raise your pool’s pH and alkalinity to dangerous levels. Furthermore, the debris can get into the pump and cause rattling noises and mechanical problems.

Another reason you should remove the debris from your pool is that it invites algae. Most algae blooms have a high pH, which means a big bloom will make it difficult to manage the pool’s pH and alkalinity.

There are plenty of reasons to get rid of algae aside from its dangerous, unsightly appearance!

Here are the most efficient ways to remove algae from your pool without chemicals:

• Pool vacuums remove debris from the bottom of your swimming pool.
• Mesh pool nets can scoop floating leaves, twigs, and other lightweight contaminants.
• Circulate your pool pump as much as possible when removing debris.
• Dump the pump basket and skimmer basket to remove caught debris.
• Clean the filter whenever the pressure gauge goes over 20 to 25.

Pool debris can be problematic, but it’s quite easy to manage with a swimming pool cover, a circulation pump, the right filter, and a vacuum.

6. Get Rid of Algae Blooms

Algae blooms cause several issues, including:

• Increased pH
• Increased alkalinity
• Corrosion
• Debris buildup
• Stains and discoloration
• Pest infestations
• Dangerous swimming environments

Furthermore, algae blooms can clog your pool filter, causing you to clean it more often than you need to.

The good news is that you can use pool shock and algaecide to treat algae blooms quickly. However, I recommend avoiding bleach to clear up a cloudy pool because it’s not the most effective solution.

If you want to remove algae blooms naturally, look for natural algaecides and phosphate treatments.

The previously mentioned Natural Chemistry Phosfree is the most natural way to remove algae’s food source from your swimming pool. You could also use the lemon juice example to treat small algae blooms.

Natural Chemistry Algae Break is made with copper to eliminate algae blooms naturally. Copper plumbing has been used to treat algae for a long time.

Each bottle can prevent and eliminate the algae without adding harmful chemicals to the water. You can swim in the pool once the initial liquid dump is fully dissolved.

Pro-tip: Don’t use copper treatments in your swimming pool if your pool has high copper levels. Too much copper can cause staining, corrosion, and buildup. I highly recommend testing your pool’s copper levels before adding any natural copper solution.

7. Pour Distilled Water into the Pool

I suggest adding distilled water into the pool. Much like the carbon dioxide example, you can install a water distiller to lower the water’s pH before it enters the pool.

Keep in mind that distilled water usually has a pH of about 7.0, which is 0.2 to 0.8 lower than your swimming pool should be. You might have to add soda ash occasionally.

Distilling water doesn’t require chlorine, fluoride, and other chemicals found in most local water sources. In fact, the process can remove these additives.

Your pool doesn’t benefit from fluoride, and it can have problems if there’s too much chlorine, copper, or magnesium found in tap water. Distilling the water helps with the pH, chemical balance, and mineral buildup.

Much like CO2 systems for pools, distilled water systems are quite uncommon. They’re typically used to monitor and adjust the pH of gunite, pebble, and plaster pools.

These materials naturally increase the pool’s pH and alkalinity, so you might have to maintain them with muriatic acid, dry acid, or the natural solutions found throughout this page.

8. Remove the Calcium Buildup

Calcium build is caused by high pH, calcium hardness, and calcium-based chemicals dumped into the pool. Calcium is one of the many chemicals needed for swimming pools, but too much of it can increase the pool’s pH.

There are two ways to get rid of the calcium buildup in your pool:

1. Use a descaler. These products remove the buildup in the pool, but they don’t eliminate the calcium concentration found in the water. Unfortunately, most descaling products aren’t natural, which means they don’t fit into the desired category of this post. However, you can brush the buildup with a pool brush to loosen the calcium.
2. Drain and refill the pool. Calcium is a solid at room temperature, which means it doesn’t evaporate with the water. You have to drain the pool to permanently remove calcium from the pool. Brush the pool thoroughly to remove the buildup, drain it ⅓ of the way, then refill it with water until it’s over the skimmer basket’s inlet.

Many pool products contain calcium, including calcium hypochlorite (powder pool shock), calcium increaser, and so on.

Draining the swimming pool also reduces the pool’s salinity. All swimming pools have salinity, even if you don’t have a salt system. Liquid chlorine and chlorine tablets use sodium chloride, which contains salt. Since salt naturally has a high pH, it increases your pool’s pH and alkalinity.

9. Use White Vinegar (or ACV)

White vinegar and apple cider vinegar will quickly and naturally lower your pool’s pH.

Much like lemon juice, you shouldn’t add more than a gallon of either solution at a time. They’re incredibly acidic and can stain and corrode your pool liner or gunite.

Another reason people choose apple cider vinegar and white vinegar is because they naturally fight algae and bacteria. Vinegar is used in countless DIY cleaning solutions, so why can’t you use it to treat your swimming pool? Circulate the pump until the vinegar dissolves, then you can swim whenever you want to.

Don’t forget to test your pool after 24 hours of running the pool pump. It’s best to make subtle adjustments rather than quickly lowering the pH.

You don’t want to have to go back and raise the pH, alkalinity, and other chemicals in the pool if you don’t have to.

Jonah Ryan

Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he’s not writing for Temperature Master, he’s usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.