How to Shock a Swimming Pool

Shocking your swimming pool can eliminate the accumulation of chloramines and other harmful chemicals. But what are the key elements to consider when shocking your pool? What are the steps to success? In this article, we guide you through the process of shocking your pool with confidence.

What Is a Pool Shock? What Types Are There?

A pool shock is a project of inputting chlorine or non-chlorine chemicals to your swimming pool to raise your level of free chlorine. When your free chlorine levels are too low, bacteria, algae, and chloramines begin to crowd your swimming pool and make it unsanitary. By shocking your pool consistently, you can create the right amount of chlorine that keeps your pool and family safe.

The typical chlorine smell that you experience around the pool does not mean that it has been cleaned. This odor exists when the chlorine in the pool gets combined with the nitrogen in oils, sweat, urine, and other bodily fluids. A potent smell of chlorine usually means that the water has been improperly treated, but it does not necessarily give you the signal when it is time to clean the pool.

So, what are the different kinds of pool shock? There are many different products that you can utilize, but here are the most popular and effective ones. For recommendations on specific pool shock products, read my guide on the best pool shock.

Calcium Hypochlorite

This chemical, also known as cal hypo, is one of the more affordable and practical strategies to shock your pool. You can usually find this at the store in a granular condition. When you are using this type of pool shock, it must get dissolved before adding to the pool. You should always be used after dusk to let at least eight hours pass before you can swim again.

Lithium Hypochlorite

Lithium Hypochlorite does not add additional calcium to your pool like cal hypo, but it is much more expensive for various reasons. It dissolves much more efficiently, but you can add it immediately to the pool without having to wait for it to disappear. Much like cal hypo, you must implement it after dusk, and you must wait at least eight hours before reentering the pool.


Out of the three pool shock types, Dichlor is the most straightforward and safest product to use. Dichlor usually contains between 50% and 60% chlorine, and it can be an excellent solution for both shock treatments and standard chlorine doses. Another superb feature of Dichlor is that you do not have to dissolve it beforehand. The product must also get used after dusk, and it must sit for at least eight hours.

What About Non-Chlorine Shock?

You may have heard about non-chlorine pool shock as an option as well. There are certain times when it is appropriate to use, so for more information please check out my guide on non-chlorine shock.

Why You Need to Shock Your Pool

Chlorine is a double-edged sword when it comes to existing in your pool. Depending on the number of people who use your swimming pool, the chlorine levels will fluctuate. Pool chlorine is designed to eliminate any existing bacteria in the pool so that it is healthy for people to swim. But it also attaches itself to ammonia in the pool, which creates terrible chemicals called chloramines.

The ammonia is a product of the sweat, urine, fertilizers, sunscreen lotions, bird droppings, and other exterior radicals that find their way into the pool. If you want a clean pool, you must break the chlorine bond (chloramine) and shock it.

When to Shock Your Pool and How Often

Shocking your pool is not a one-time thing that you should occasionally do. It is a lifelong process that takes focus and discipline. It would be best if you kept a log by your pool to stay on top of shocking it consistently.

If you are operating on a weekly oxidizing and shocking schedule, you should alternate between a non-chlorine and chlorine shock each week. This system makes chlorine much more effective when it gets implemented, but it will lower the amount of chlorine required.

So, when are the specific circumstances where you must shock the pool?

Rain and thunderstorms are not always things we can plan for, but you should try and shock your pool afterward. While the storm is occurring, your swimming pool will get contaminated by rainwater, debris, and dust. Algae outbreaks are also a key signal for pool shocking. When the algae begin to pop up, you should utilize a shock type with extra chlorination or other cal hypo alternatives.

You should also make sure to shock your pool when you are opening and closing for the season. After you have balanced the other chemicals, you can shock the pool so that you can eliminate any bacteria, make the water clear, and oxidize any particles. Lastly, if you have many people use the pool at once for a party, the water can get contaminated quicker. It is also essential to shock it after these events too.

Step-by-Step: How to Shock a Swimming Pool

If you want to shock the pool successfully, you should aim to raise the free chlorine level 10 times greater than the number of chloramines. When you reach this ratio, it will effectively break up those harmful bonds and make your pool clean again.

The first step in shocking the pool is to test the water and calculate the current ratio. You should monitor the pH level to measure the free chlorine (FC) and total chlorine (TC) of the swimming pool. To find the individually combined chlorine (CC) level, you deduct the FC from the TC. Once you see this number, you now know how much chlorine will need to be added to the pool.

The next step is calculating the optimal amount of shock that you will need to mix up. It is smart to confirm the number on the packaging of your shocking chemical product that you decide to use. Around this time, you should also prepare the shock well ahead of schedule in a 5-gallon bucket. The benefit of this is the time saved and the possibility of performing an incorrect calculation.

Next, you should ensure that the pool pump operates effectively so that the pool shock can mix in the pool. After confirming the pool pump works well, you can dump the pool shock solution into the water’s outer edges. Once you input the pool shock into the water, you can be patient and allow the pump to keep running for at least six hours.

After you have let the time pass, you can then test the water once again to confirm the optimal chlorine levels are present in the pool. It would be best if you looked to see that the free chlorine level is ten times greater than the combined chlorine levels.

If you’re still having trouble getting your pool in the right spot, you may need to SLAM your pool.

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Wrapping Up

As you can see, there is a system that goes along with shocking your pool, but the process is not too complicated. You must decide on a quality pool shock product or two that fits your needs, and then narrow down a consistent pool maintenance schedule. Once you run through the pool shock instructions carefully a few times, you will soon be a maintenance professional that keeps your pool safe and clean.

Questions? Shoot us a note and we’ll be happy to help.

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