Sodium Bisulfate

Sodium Bisulfate (Dry Acid) For Pools - What Does It Do?

Sodium bisulphate, also known as dry acid for pools, is a product that is used to alter the chemistry of your water. Unlike comparable acidic solutions, sodium bisulphate comes in a granulated form, making it safer to handle and reducing the risk of chemical burns.

In this article, we will discuss when to use sodium bisulphate in your pool, safety considerations for this product, and how to add this dry acid to your pool.

When To Use Sodium Bisulphate In Your Pool

Sodium bisulphate, also known as sodium bisulfate or dry acid, is used to lower the pH and total alkalinity levels in your pool.

These two properties combined refer to the overall acidic or alkaline state of your water, which should be ideally balanced for optimal swimmer comfort as well as the longevity of your pool’s infrastructure.

Ideal levels of total alkalinity in a pool range from 80-120 ppm (parts per million), while the ideal pH range for swimming pools lies between 7.2-7.6.

If your pool’s total alkalinity or pH levels are reading at values _above _these ranges, it is appropriate for you to use sodium bisulphate to lower them.

Safety Considerations For Sodium Bisulphate

Sodium bisulphate is a dry acid, meaning that it exists in a granulated or powdered form. While dry acids are considerably safer than their alternatives, such as hydrochloric acid which can be used for the same purpose, there are still some safety precautions you should observe.

Although this acid is in a granulated form when stored, sodium bisulphate immediately produces an acid solution when it mixes with moisture.

This is intended to happen inside your pool or a mixing bucket, but it is also possible for dry acid to get in contact with moisture on your skin and form a dangerously corrosive solution.

Sodium bisulphate is also at more risk of becoming airborne than its alternative, hydrochloric acid. Small particles of dry acid can easily be stirred up in areas with excessive wind and can form small amounts of corrosive fluid if it enters your airways.

How To Add Sodium Bisulphate To Your Pool

Gather Supplies

To add sodium bisulphate to your pool, you will need a nonmetallic mixing bucket, a stirring utensil, pool water, protective gloves, eyewear, and an environment protected from wind.

You will also need a chemistry test kit that is capable of measuring both your pool’s pH and total alkalinity.

Test Your Pool’s Chemistry

Immediately before you plan to make adjustments to your pool’s total alkalinity and pH, test the pH and alkalinity levels in your pool so that you have the most precise readings to work with. Remember that you can only use sodium bisulphate to _lower _these levels.

Calculate A Dose For Your Pool

Next, calculate a dose for your swimming pool. This can be done using the information on your product’s packaging, or using our handy pool acid dose calculator.

To use the calculator, you will need to know your pool’s volume, your current pH and total alkalinity readings, an ideal total alkalinity OR pH reading, and the concentration of your selected dry acid. Most products have a concentration of about 92%.

It is important to avoid adding too much dry acid to your pool, as this can produce undesirably low levels of pH and low total alkalinity which lead to corrosive water.

If you are unsure about how much sodium bisulphate to add to your pool, it is always best to start with a smaller amount and add more later when necessary.

Add And Circulate The Product

Carefully measure out a dose of dry acid that is suitable for your pool in accordance with your product’s concentration. Always wear gloves and eye protection when handling sodium bisulphate, and take care to prevent particles of it from becoming airborne.

Afterwards, fill a bucket 3/4ths of the way up with pool water, add the dry acid you have measured out, and mix until the granules are fully dissolved. You can then distribute this mixture around the perimeter of your pool while the pump is running so that it is thoroughly mixed.

You should then leave your pump running for a minimum of six hours before retesting your pool’s pH and total alkalinity. If you do not wait at least this long, you are likely to get inaccurate results.


Sodium bisulphate, or dry acid for pools, is an effective product for lowering the pH and total alkalinity levels of your pool. This product is available in a granulated form, making it much safer to handle than its alternative: hydrochloric acid.

Do you have any questions about sodium bisulphate or how to use it in your pool? Leave us a comment down below, we’d love to help out!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.