Pool Chemistry Shock Chlorine Vs. Non-Chlorine

There is a lot of work that goes into keeping the water clear and safe in a swimming pool. Chlorine application, proper filter use and skimming for debris are just some of the tasks that must be performed on a regular basis. Shocking the pool every few weeks is another important part of maintaining the pool and you may wonder whether it's better to use a chlorine or non-chlorine shock method. While both methods work, there are some differences to consider.

Swimming pools need to be shocked on occasion so that chlorine works properly.


Both chlorine and non-chlorine shock treatments are designed to destroy organic matter and ammonia compounds found in pools and spas. These compounds are introduced by swimmers' urine, saliva and sweat. Algae, tree debris and windblown dust also contaminate the water. Both pool shocking methods increase the amount of free chlorine in a pool to help destroy these compounds.

Method of Action

When added to a swimming pool, chlorine forms hypochlorous acid, which oxidizes any existing ammonia. Large amounts of chlorine must be added during a shock because it takes 7.6 parts of chlorine to oxidize one part of ammonia. For dirty pools, up to 25 parts of chlorine may be needed for sanitation. Non-chlorine shock treatments also destroy organic contaminants and ammonia, but rather than killing or disinfecting the entire pool, they control the level of organics and chlorine and make sure the chlorine can properly sanitize on its own. Non-chlorine treatments do not bleach or leave residue on vinyl liners or swimsuits, nor do they add excess calcium to the water that can cause deposits on pools.

Swimming Timeline

Both chlorine and non-chlorine shock treatments generally allow swimming within 15 minutes of application. If a large amount of chlorine is added during a shock, however, it can take several days for chlorine to drop to a safe level for swimming. If too much non-chlorine shock is added, no extra waiting is necessary.

Ease of Use

Determining the amount of chlorine it will take to shock a pool can be complicated and requires calculations of the amounts of free chlorine available. Non-chlorine shock chemicals are generally added at a consistent rate of 1 pound per 9,246 gallons of water per week and require less calculation.


Both treatments, when used properly, are equally reliable in improving the quality of a swimming pool. However, adding too much or too little chlorine is a common problem that occurs. If too little chlorine is added, it can lead to burning eyes and skin irritation. Any amount of non-chlorine shock that is added to the pool will generally improve its condition. They prevent the formation of chloramines, which cause eye and skin irritation. They also do not cause cloudy, dull water that smells strongly of chlorine.

Storage Safety

Chlorine shock chemicals can be dangerous to store as they are flammable and can release chlorine gas. Non-chlorine shock treatments are non-flammable and do not release these gases. They will not burn the skin when handled.