How Long To Wait Between Adding Chemicals

How Long To Wait Between Adding Pool Chemicals?

Many different pool chemicals have hazardous warning labels and handling instructions that need to be followed carefully. While it’s always good to exercise caution, not all pool chemicals cause severe interactions when they combine.

In this article, we will discuss the average recommended waiting time that you should wait between adding different chemicals to your pool, as well as a list of chemicals with notable interactions that require a longer than average waiting time.

The average recommended amount of time that you should wait between adding different types of pool chemicals or treatments is considered to be around 10 minutes.

This is because 10 minutes of time with your pump running is typically enough time to reasonably disperse any chemical treatments into your water, which will dilute them enough to prevent any unwanted interactions.

Although this precaution is recommended, most chemicals are perfectly safe even if they come in contact with each other before this waiting period is complete.

Although chemical ineffectiveness may occur in this case, it is not as severe of a problem as what can occur when certain chemicals are combined.

Regardless of what happens in the water, pool chemicals should never be mixed together directly outside of your pool, as this can be incredibly dangerous.

Cal Hypo

Certain pool chemicals are known to be highly interactive with others. Among these is cal hypo or calcium hypochlorite, a type of granulated chlorine that is most often used as a shock treatment.

Cal hypo shock can have severe interactions with other chlorine products like dichlor and trichlor which can generate explosions and lead to chemical burns. Cal hypo can also lead to the development of cloudy water or calcium stains if it is used too closely in conjunction with any pH altering chemicals.

When needing to add further products to your pool following a cal hypo shock treatment, you should wait for a minimum of 24 hours to reduce the chance of negative interactions from occurring.

Hydrochloric Acid

Hydrochloric acid is a chemical that should not be added to your pool at the same time as any chlorine compounds.

Hydrochloric acid can react with chlorine compounds to produce a highly toxic gas, so it is best to allow this acid to circulate in your pool for a minimum of one hour before adding any chlorine.

Copper Algaecides

Although algaecides that contain copper are not known to cause dangerous chemical interactions, we recommend observing a waiting period following their use for other reasons.

Although copper is a highly effective sanitising agent, when it interacts with high concentrations of chlorine, it can cause stains to develop on your pool.

To prevent copper algaecide stains from forming on your pool, it is essential to wait at least 24 hours after introducing a copper algaecide to perform a shock treatment.


Although exercising safety and precaution is never a bad thing when it comes to handling chemicals, there is no need to be overly afraid. Most pool chemicals are created with consumer’s safety being a top priority.

Do you have any questions about how long to wait between adding pool chemicals? Let us know in the comments down below!

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.