Pool chemical safety: handling, mixing and storage
Pool chemicals are safe when used as directed, but they're strong. The most serious accidents come from a few avoidable mistakes: mixing products, adding water to dry chemicals, and storing incompatible products together. Read the label of every product you use, since it carries the specific directions and warnings for that product.
The rules that matter most
- Never mix pool chemicals with each other. Not in a bucket, a scoop, a feeder, the skimmer or the pump basket. Add each one to the pool separately.
- Never mix chlorine and acid. Chlorine products (liquid chlorine, bleach, cal-hypo, dichlor, trichlor) react with acids (muriatic acid, dry acid) to release toxic chlorine gas.
- Never mix different chlorine products. Cal-hypo and trichlor (or dichlor) can react violently, causing fire or an explosion. Don't put cal-hypo in a trichlor feeder, and don't use the same scoop for both.
- Add chemicals to water, never water to chemicals. When you pre-dissolve a granular product, fill the bucket with water first and add the chemical slowly. Water added to concentrated acid or certain dry chemicals can spatter or react violently.
- Keep the pump running while adding chemicals, and wait for each one to circulate (an hour or more) before adding the next.
Protect yourself
- Wear splash-proof eye protection and chemical-resistant gloves, especially with acid and liquid chlorine.
- Open containers outdoors, with your face away from the opening, and stand upwind.
- Pour close to the water surface to avoid splashes.
- Use clean, dry, dedicated scoops and buckets, one for each product, and label them.
- Keep children and pets away while you handle chemicals, and keep everyone out of the pool until chemicals have mixed in and levels are back in the swimming range.
Storage
- Keep products in their original, closed, labeled containers. Never pour chemicals into food or drink containers.
- Store acids and chlorine products apart. Ideally in separate cabinets or on opposite sides of the room, and never with acid stored above chlorine where a leak could drip onto it.
- Keep them cool, dry, out of direct sun and away from heat sources, fuel, fertilizers, paint and other chemicals.
- Store them out of reach of children, ideally locked.
- Liquid chlorine slowly loses strength and builds up pressure. Buy it as you need it, and store it upright and shaded.
- Dispose of unwanted chemicals through your local household hazardous waste program, not in the trash or down the drain.
The order to add chemicals
When several adjustments are needed, a sensible order is: alkalinity, then pH, then calcium, then stabilizer, then chlorine. If the water is green or unsafe, add chlorine first. Either way, one product at a time, with circulation in between. The pool chemical levels guide explains the reasoning.
If something goes wrong
- Chemical in the eyes: rinse with clean running water for at least 15 minutes and get medical help.
- On the skin: remove contaminated clothing and rinse the skin with plenty of water.
- Gas, fumes or a reaction in a container: leave the area, move upwind, keep others away, and call 911 if anyone has trouble breathing or the reaction continues.
- Swallowed, or any other exposure question: in the US, call Poison Control at 1-800-222-1222. Have the product label with you.
- Spills: follow the product label's spill instructions. Don't sweep spilled chlorine and other chemicals together, and keep spilled chlorine away from organic materials such as leaves or oil.
Frequently asked questions
Can I add chlorine and acid on the same day?
Yes, as long as you add them separately to the pool, at different spots, with the pump running and some time between them. The danger is mixing them while concentrated, before they're diluted in the pool.
Can I store pool chemicals in the garage?
Many people do. Keep them away from cars, fuel, fertilizer, lawn chemicals and heat sources, with acids and chlorine separated, and out of children's reach. A garage that gets very hot in summer will shorten liquid chlorine's life.
Is it safe to use household bleach?
Plain, unscented bleach is the same chemical as pool liquid chlorine, at a lower strength. Avoid scented, "splash-less" or thickened bleaches, which contain additives.