Swimming pool and spa chemicals

Keeping swimming pool and spa water safe

Swimming pool or spa water that hasn’t been sanitized properly can make people sick. Possible illnesses include ear infections, stomach infections and skin rashes.

Microorganisms like bacteria and viruses can live in swimming pool and spa water. Even clear water can have microorganisms in it. Maintaining proper water balance with sanitizers reduces the numbers of microorganisms to safe levels.

To keep your pool or spa water safe, you must test the water on a daily basis, especially during times of high use. It is important to always maintain proper water balance in all types of pools and spas, even inflatable pools.

Controlling algae

Algae are plant-like organisms that live in water. Hot weather, sunlight, and low sanitizer levels can encourage algae growth. Algae are not usually harmful to people, but they can pose a hazard by making pool and spa surfaces slippery and the water cloudy. Algae can also make sanitizers less effective, because when more sanitizer is used up to control algae, it becomes easier for bacteria and viruses to multiply.

Maintaining proper sanitizer levels should prevent excess algae growth. For big algae problems, algicide products containing copper sulphate or quaternary ammonium compounds can help. Devices that release copper metal ions into pool or spa water can also be used to control algae.

Testing the water

To keep swimmers and bathers safe, you must test your water balance daily for sanitizer levels, pH, total alkalinity, and calcium hardness. Water testing can be done using good quality test kits available in stores. You can also bring water samples to your swimming pool or spa dealer.

How to sanitize pool and spa water

Whether you choose chemical products or electrical devices to sanitize your pool or spa water, you must maintain a certain amount of sanitizer to prevent disease-causing microorganisms from multiplying. You must also maintain proper water balance and the right concentration of copper-based algicide to prevent staining pool surfaces.

The exact amount of sanitizer you need depends on many factors:

  • the number of bathers
  • how often you use your pool or spa
  • contaminants in the water (like suntan lotions and oils)
  • water temperature
  • the amount of recent rain

Ask a pool and spa professional what the right treatment is for your pool or spa.

Traditional pools or spas

Use chlorine- or bromine-based products as sanitizers; these also control algae. You can buy chlorine and bromine as a chemical (puck, tablet or liquid) or buy a device that creates chlorine from salt to clean the water. Some types of chlorine or bromine can also be applied using a dispenser.

Saltwater pools or spas

Use a device that sanitizes the water by generating chlorine from salt added to the water.

Use a registered or scheduled product

All pool and spa sanitizers and devices used to control microorganisms must be registered or scheduled under the Pest Control Products Act. Health Canada scientists review product applications for possible risks to human health and the environment, and to ensure the product is effective. Products will only be authorized for use if they can be used safely.


Only use a registered or scheduled product and follow all label directions.

Registered products will have a Pest Control Product number on the product label, such as:

  • Reg. No. 00000 P.C.P. Act
  • Registration No. 00000 Pest Control Products Act

Scheduled product labels will say "Scheduled under The Pest Control Products Act.”

If you are in doubt about whether a product you are considering is covered by the Pest Control Products Act, contact the Health Canada Pest Management Information Service.

Other pool and spa products like pH adjusters, shock treatment, chlorine neutralizers, and devices used only to dispense pool and spa chemicals, do not have to be registered. This is because they are not intended to control disease-causing microorganisms or algae.

Recommended minimum levels of sanitizer

The level of sanitizer in your pool or spa water is called "free available chlorine or bromine”.

The recommended minimums are:

  • 1-3 ppm for residential pools, including inflatable pools
  • 3-5 ppm for residential spas and hot tubs
  • for commercial pools and spas, follow provincial and/or municipal regulations

Organic matter like tree leaves, grass, bugs and suntan lotion makes sanitizers less effective. In some cases, the label directions on swimming pool sanitizers and algicides may tell you to maintain a minimum chlorine level of 0.6 ppm. Reducing sanitizer levels from 1-3 ppm to 0.6 ppm should only be done when you control the organic matter in your water. Note that this applies to pool water only.

Spa water must be maintained at 3-5 ppm.


The label states how much sanitizer to use and how to handle the product safely. Always read the label before using any sanitizer.

Using pool and spa devices

There are four types of devices used in swimming pools and spas:

  1. Chlorine generators that use electrical energy to produce chlorine from salt, which in turn sanitizes the water. Chlorine generator devices must be registered by Health Canada.
  2. Chemical dispensing devices that automatically release chlorine or bromine sanitizers into the water. The user's manual must be carefully followed. Chemical dispensing devices for use in swimming pool and spa water do not have to be registered.
  3. Ionizers that produce copper metal ions to control algae. Chlorine-based or bromine-based products for sanitizing must still be used. Ion and sanitizer levels should be checked often, and electrodes replaced as needed. Ionizers must be registered.
  4. Ozone-generating devices that can be used to reduce organic matter in pool and spa water. The main purpose of an ozone-generating device is to oxidize organic matter. These devices should be used with chlorine-based or bromine-based sanitizers, and are not meant to replace them. Ozone-generating devices do not have to be registered, unless they claim to control microorganisms like bacteria and viruses, or to control algae.

When using ionizers or ozone-generating devices, you must still use chlorine- or bromine-based products for sanitizing. A proper level of sanitizer must be maintained in order to prevent the spread of disease-causing microorganisms.


Swimming pool and spa devices that generate or dispense a sanitizer have detailed instructions in the user's manual, on the package and on the device itself. Always read the label and the user's manual before installing and using a device.

Using copper sulphate algicides

Copper sulphate-based swimming pool algicides can be used to:

  • control algae
  • improve water clarity
  • reduce the amount of chlorine- or bromine-based products needed

They do not:

  • control microorganisms like bacteria and viruses
  • eliminate the need for sanitizers

Copper sulphate-based products must be used along with chlorine- or bromine-based sanitizers to protect bathers.

The amount of copper sulphate-based algicide needed will vary depending on the size and type of your pool and its location, for example how much sunlight it receives.

Note: Using copper sulphate-based algicides in swimming pools is not dangerous to swimmers. If you follow all label directions, copper sulphate algicides should not cause skin irritation. However when handling undiluted products, care must be taken to reduce the risk of skin irritation.

Safety tips

When using swimming pool and spa chemicals

  • Keep all chemicals away from children and pets.
  • Keep chemicals away from food surfaces like counters, tables, and stovetops.
  • Wear proper protective equipment and clothing, like gloves, goggles, and footwear.
  • Use separate, clean metal or plastic measuring cups for each chemical when measuring.
  • Add the chemical to the pool water (unless otherwise noted on the label).
  • Avoid generating dust when cleaning up a powder or solid. The dust can react with moisture on your skin and cause injury.
  • Wash your hands with soapy water after handling any chemical.

Do not:

  • smoke, drink, or eat while using chemicals
  • use contents of unlabeled containers
  • mix different chemicals together or put spilled chemicals back into their containers
  • touch undiluted chemicals with your hands
  • expose chemicals to heat or flame

If a fire breaks out, use large amounts of water. Do not use a "dry chemical" fire extinguisher. If you can't extinguish the flame immediately, leave the area and call the fire department.

After using swimming pool and spa chemicals

  • Read and follow storage instructions on the product label
  • Store chemicals:
    • in their original containers
    • in a cool, dry, well ventilated place, away from sunlight
    • away from food and beverages
    • away from gasoline, fertilizers, pesticides, grease, paints, tile cleaners, turpentine, or other flammable materials, especially when pool chemicals are stored in sheds or small storage rooms
  • Store liquids below powders or solids
  • Throw out unused or partially used products at provincial or municipal household hazardous waste disposal sites

Do not

  • stack containers or store materials or chemicals above your head
  • reuse empty containers – instead, throw them out in your household garbage

In case of accidental poisoning or injury

  • Get medical help or call a poison control centre right away.
  • In case of accidental poisoning of a pet, get veterinary help right away.
  • Remove the victim from the source of contamination and quickly remove contaminated clothing and shoes.
  • Flush the contaminated area with lukewarm, gently flowing water for at least 15–20 minutes (longer for corrosives).

Report pesticide incidents

Report pesticide problems to the manufacturer listed on the label. They must report problems to Health Canada.

Page details

Date modified: