How to Lower pH Level in Your Pool Safely

Pool care is an absolute must for any swimming pool owner. Getting rid of twigs and mud is easy, but maintaining the pool’s chemical balance is often a bit tougher. Many homeowners struggle with pool chemistry and at the top of their problems is how to balance pH level.

A spike in your pool’s pH can cause many issues, be it eroding equipment or causing skin irritation. Luckily, there are a few ways of fixing this problem. In this extensive guide, we detail the safest way to lower pH level in your pool.

What Causes High pH Levels?

The normal pH of pool water is between 7.2 and 7.6. We consider 7.4 as the optimum pH. However, you shouldn’t be worried if this value isn’t exactly 7.4. It’s perfectly normal for your pool’s pH to occasionally fluctuate.

You should be concerned if the value frequently goes beyond 7.8. High pH levels mean your pool’s water is very alkaline.

Water pH is extremely unstable, and many factors contribute to its surge. Below are the most common causes.

Pool Shock

Shocking your pool is vital, but you should do it in moderation. Pool owners use chemicals like calcium hypochlorite, sodium hypochlorite, and sodium Dichlor.

If you use calcium hypochlorite (cal hypo), you need to be extra careful. Although cal hypo is neutral, when mixed with water, its pH can surge past 10.

Runaway Alkalinity

High total alkalinity (TA) levels can raise your swimming pool’s pH. TA functions as a buffer that inhibits pH fluctuation. However, you should carefully pick the chemicals you use to increase the alkalinity of your pool.

Most individuals use sodium carbonate (soda ash) to increase TA. The problem with sodium carbonate is that it has a high pH of 11.3-11.6. This range may increase the pH levels of your pool.

Improperly Measured Chemicals

To maintain a pool’s chemical balance, you have to use the right chemicals and, more importantly, the right amounts of chemicals. Excess quantities might cause either high or low pH levels.

Carbon Dioxide Loss

From our experience, the loss of carbon dioxide (CO2) from pools can account for high pH levels.

Carbon dioxide transforms to carbonic acid when it dissolves in water. The pH of this acid is low, meaning it lowers your pool’s alkalinity.

The CO2 concentration in water should be similar to that in air. Carbon dioxide dissolves into and out of the pool’s water until an equilibrium is reached.

The presence of algae in water primarily causes carbon dioxide loss. Algae consume CO2 and, in doing so, prevent the formation of carbonic acid.

Other factors that may cause CO2 loss in pool water include splashing and aeration.

Importance of Lowering Pool’s PH to The Right Range

You’ll encounter lots of problems if your swimming pool’s pH constantly rises.

Unhealthy to Swimmers

High pH levels in a pool can be a health hazard to swimmers. Swimmers might experience:

  • Red, irritable eyes
  • Dry skin
  • Skin rashes

Apart from the health effects, a surge in the pool’s pH affects swimming gear. You’ll notice premature wear and tear of swimming suits and goggles.

Lowers Chlorine Efficiency

Chlorine becomes less effective when the pool’s pH levels are high. When chlorine interacts with water, it forms hypochlorous acid. This acid is responsible for inactivating all pathogens in water.

Hypochlorous acid functions best in acidic conditions. If the pH is too high, hypochlorous acid will not kill all the microorganisms in your pool.

You have to find a compromise pH that is safe for swimming and doesn’t curtail the effectiveness of hypochlorous acid.

Causes Scaling

High alkalinity makes pool water hard. And we know hard water is susceptible to scale formation from calcium deposits. The build-up of scales may block or clog your pool’s pipes and filters.

Clogged filters and pipes affect water circulation and may significantly strain your pool equipment. Your pool might face issues like motor failures or even leaks. In the end, you incur considerable costs in replacing pool equipment.

Poor Water Quality

High pH levels affect the water quality in your pool. As mentioned above, chlorine is less effective in killing algae when the water is very alkaline. Algae boom will certainly cause cloudiness in your swimming pool.

Very high pH also affects the solubility of chemicals like calcium. You’ll notice cloudy water if such chemicals don’t dissolve.

You can avoid the mentioned issues by maintaining the correct chemical balance in your pool. We recommend testing your pool before and after adding chemicals. The key things to check are pH, total alkalinity, and acid demand.

If you notice the pH levels are high, you should work immediately to restore the right balance. There are two chemicals you can use to lower PH levels in pools. The two products are:

  • Sodium bisulfate
  • Muriatic acid

The industry term for these products is pH Reducers. Some brands refer to them as pH Minus. When shopping, you must be keen on which product you want to use. Muriatic acid is more potent than sodium bisulfate.

Sodium Bisulfate

Sodium bisulfate is a dry acid that forms when sulfuric acid reacts with a base like sodium hydroxide or sodium chloride. Although reactions between acids and bases yield neutral products, sodium bisulfate is only partially neutralized. It has an acidic pH of about 1.

Sodium bisulfate has many names. You may call it dry acid, bisulfate of soda, sodium hydrosulfite, sodium hydrogen sulfate, sulfuric acid sodium salt, monosodium hydrogen sulfate, acid salt, or niter cake.

Is It Safe?

Sodium bisulfate is a safer product compared to muriatic acid. It comes as a fine powder, meaning you need to be cautious when using it in windy conditions.

How to Lower pH Levels Using Sodium Bisulfate

When it comes to pool maintenance, dry acid primarily acts as an acidity regulator. You use it to curb runaway pH levels of your pool water.


Avoid using sodium bisulfate during windy conditions. The wind can easily blow this powder back into your eyes, hands, or skin. You have to use this product when you’re near the pool.

A few things you’ll need include:

  • A pool test kit
  • A plastic bucket. Do not use metallic containers
  • A stirring rod (wooden or plastic)
  • Safety equipment like gloves and glasses
  • A measuring cup (plastic)
  • Sodium bisulfate
  • A plastic scoop

Once you’re set, follow these steps.

Step 1: Test the PH

It’s always advisable to test your pool water before applying PH reducers. The ideal PH range should be between 7.2 to 7.6. If you find the PH is above 7.6, proceed and use sodium bisulfate.

Step 2: Decide the Quantity to Add

The quantity you should add depends on the pool size and the manufacturer’s instructions. It may also depend on how high your pool’s pH is.

We recommend only adding three-quarters of what the manufacturer suggested. You’re unlikely to add excess dry acid if you follow this rule.

Step 3: Add the Sodium Bisulfate

Once you measure the ideal amount, pour the powder into the pool near the return jets. Avoid adding sodium bisulfate near the skimmer.

Some manufacturers advise pre-dissolving sodium bisulfate in a bucket before adding it into the pool. If you pick this option, ensure you add the dry powder to water and not the other way.

Afterward, turn on the pool to evenly distribute the sodium bisulfate granules. If you don’t have a pool pump, you can use a paddle to circulate the water manually.

Step 4: Allow the Sodium Bisulfate to Dissolve

Dry acid doesn’t work instantly. It needs time to dissolve before it does its job.

Step 5: Re-test the Pool’s PH

After waiting for several hours (about six hours), re-test your pool’s pH. If the levels are still high, you need to repeat the entire process. This time ensure you add the sodium bisulfate slowly.

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Muriatic Acid

Muriatic acid is an impure form of hydrochloric acid. It’s a caustic acid with a pH of about 1-2. Homeowners mostly use it to wash tiles, clean bricks, and clear drains.

Pool owners use this acid to offset high pool pH levels.

Is It Safe?

Muriatic is a very corrosive acid. It’s capable of corroding anything, be it clothing or metal.

This acid is safe for home use, provided you take safety measures and follow the manufacturer’s instructions.

How to Lower pH Levels Using Muriatic Acid

If you suspect your pool’s pH is high, it might be time to add muriatic acid.


Muriatic acid comes in liquid form. It can burn your skin at the slightest contact, and its fumes can affect your respiratory system. You must handle this acid using protective gear.

We recommend the following things.

  • A chemical-resistant apron
  • Acid-resistant gloves
  • Safety goggles
  • A plastic bucket
  • A stirrer (wooden or plastic)

Once you’re ready, follow this guide

Step 1: Test the Pool’s PH

Your pool’s pH range should be between 7.2-7.6. If it’s higher, consider lowering it using muriatic acid.

When testing the pH, you can use test strips, differential sensors, or process sensors.

Step 2: Wear Protective Gear

Before handling muriatic acid, you must wear protective clothing. We urge you to wear acid-resistant gloves, safety goggles, and a chemical-resistant apron. Make sure the apron covers your legs and hands.

Step 3: Measure and Dilute the Muriatic Acid

The ideal amount of acid to use is indicated in the manufacturer’s instructions. You may need to dilute muriatic acid before adding it to the pool. Diluting the acid makes it less dangerous during splashes. Always add the acid to a water bucket and not water to the acid.

Step 4: Turn on the Pump

Turning the pump on or off is a matter of preference. Some claim that when the pump is on, it adds oxygen to the acid and amplifies the pH levels.

However, we recommend turning the pump on due to the strength of the acid. Muriatic acid might corrode the pool’s floor if left too long in one section.

Step 5: Add the Muriatic Acid

Walk around the pool while slowly pouring the acid. Concentrate more in the deep end of the pool. After you’re through, ensure you rinse off the bucket.

Step 6: Let It Work

It may take up to 30 minutes for the acid to disperse into the pool water. During this period, ensure no one enters the pool.

Step 7: Re-check the PH Levels

Re-test the water after 3-4 hours to ensure the pH levels are optimal. If they are off, add more muriatic acid until you achieve the ideal levels.

Final Safety Tips

It’s advisable to exercise caution when adding muriatic acid and sodium bisulfate to your pool. Always ensure you:

  • Wear protective gear
  • Don’t mix these products with chlorine. Such a combination produces toxic fumes
  • Add the acid into a bucket of water and not the other way round
  • Only use three-quarters of the recommended portions
  • Do not use the pool a few hours after adding pH reducers
  • Use plastic buckets

And that’s about it. Don’t be intimidated by either of these methods for lowering your pool water’s pH level. If you overshoot it, make sure to check out my article on how to raise the pH level in your pool.

Questions? Let me know.

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