Shock Treatment

What is Pool Shock Treatment?

Pool shock is either chlorine or non-chlorine chemicals that you add to the pool to destroy any contaminates in the water. The goal is to raise the free chlorine levels to a point where it will destroy any algae or bacteria growing in the pool.

Free Chlorine Versus Total Chlorine
Understanding the different types of chlorine found in a pool can be difficult to understand. Free chlorine is the chlorine that is typically tested for to determine the proper chlorine levels for a pool. Basically, free chlorine is the chlorine available in the pool that can work to destroy contaminants. Total chlorine levels includes the chlorine that has already joined with the contaminants in the pool to destroy them.

When testing your pool, the amount of free chlorine should equal the total chlorine to make sure that you have enough chlorine present to destroy bacteria and other contaminants in your pool.
Pool shock will greatly raise the free chlorine levels in your pool to quickly destroy any bacteria found in your pool. Remember, be sure your chlorine levels have returned to a safe level before you go swimming.

Types of Pool Shock
There are two main types of pool shock:

Chlorine
Non-Chlorine


Chlorine shock basically involves raising the chlorine to very high levels in order to destroy any contaminates in the water. Typically, a chlorine based shock will rise the chlorine level to 10 ppm. The problem with chlorine shock is you must wait for the levels to drop down to normal levels, around 3 – 4 ppm, before you can swim. This takes time and you must test your water to be sure the levels have dropped.

Non-chlorine treatments generally use potassium monopersulfate. This chemical is very good at oxidizing contaminants but will not kill bacteria. The biggest benefit of this type of shock is you don’t have to wait as long before you can begin using the pool. Most of these types of shocks say you can swim 15 minutes after using it although many pool experts recommending waiting overnight.


Why Do You Need to Shock Your Pool?

It’s important to understand why you need to shock your pool. Any time humans enter the water, they introduce organics and other contaminants into the water. These include sweat, saliva, skin cells, body lotions, urine and many other things. Mother Nature also contributes her share of contaminants as well by blowing leaves and dirt into the pool or by diluting the water when it rains.

These contaminants provide a food source for both bacteria and algae to grow. This is why we had sanitizers such as chlorine to the pool. Sanitizers will:

Kill bacteria and algae growing in the pool
Breakdown the contaminants, removing them from the water

If you keep your pool at the proper chemical balance, you won’t have to worry about shocking your pool. But if your pool’s chlorine levels drop too low, you will need to shock your pool to raise the chlorine levels to ensure a safe swimming environment.


When Should You Shock?

Believe it or not, you may not need to ever shock your pool if you practice good water care at all times. However, during the winter months most people don’t spend much time checking the chemical levels in their pools.

During the summer months, you must be sure you maintain the proper levels of free chlorine in the pool. If it falls too low, you will need to shock your pool to bring the levels up to a normal level.

Even if you take great care maintaining the proper chlorine levels in your pool, there are still other times when you may want to shock your pool anyway to be sure the water remains clear and safe for swimming.

​Some of the most common times are:

After heavy pool use
After a heavy rain or windstorm
After a water change


Shocking your pool is one of the easiest ways you can make sure your pool remains clean and clear all summer long. But, if you continue to test your water and keep it in proper balance, you will not have to worry about shocking your pool very often. If you don’t maintain the proper chemical balance in your pool however, you may need to shock it more often to ensure that your water is safe for swimming when you or your family and friends are ready to dive in for a swim.

It might be advisable to shock the pool water once a month depending on how often the pool is used. If you’re on top of your chemicals and your pool is in good chemical standing, then you don’t have to shock as often as normal, but it also doesn’t hurt to keep bacteria at bay.

Note, However, If you’re a heavy pool user surrounded by trees, I would shock every week to make sure your pool is always protected.