How to Shock a Swimming Pool

When the summer months finally come around and it is time to prepare your pool, shocking is an inevitable process. Shocking your swimming pool will eliminate the accumulation of chloramines and that strong chlorine smell. It will also help kill bacteria and algae that have built up over time, and clear up cloudy water. Are you not quite sure where to start? In this article, I’ll guide you through the process of shocking your pool with confidence.

Let’s get right into it with the steps that swimming pool owners need to take to shock your pool successfully. If you’re a little more unfamiliar with the shocking process, skip down and read about how shocking works, types of shock, when to shock, and other tips.

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 to about ten times higher than the number of chloramines. This ratio will effectively break up those harmful bonds and make your pool clean again. Let’s start with some supplies you need and then get into the steps for shocking your pool.

Supplies Checklist

  • Water testing kit
  • Enough pool shock to fix your chlorine ratio
  • A mixing bucket
  • Personal protective gear (Glasses, gloves, and full cover clothing)
  • Brush or pool vacuum for final touch-ups

Step 1: Test the Pool Water

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 calculate this number, you now know how much chlorine you will need to add to the pool.

Step 2: Calculate the Amount of Shock to Use

The next step is to calculate the optimal amount of shock to prepare. Check the instructions on the packaging, use my pool calculator to determine the volume of your pool (i.e. how many gallons of pool water you have), and use my pool shock calculator to determine the amount of shock you need to add. Most types require you to mix shock in a bucket to dissolve.

Step 3: Make Sure the Pump Is Working

Next, you should ensure that the pool pump and pool filter are operating at full power so that the pool shock can mix in the pool.

Step 4: Dump Shock 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 dump the pool shock into the water, allow the pump to keep running for at least six hours. Grab a drink and relax a bit!

Step 5: Test the Water Again to Check for Optimal Chlorine Levels

After those six or more hours, you should test the water once again to check for proper chlorine levels and other pool chemicals. You should aim for ten times more free chlorine 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.

Here’s a good video on the entire pool shocking process outlined above.

What Is a Pool Shock? What Types Are There?

Shocking your pool is an important part of your regular maintenance routine. When you shock your pool, you are essentially adding more chlorine (or non-chlorine chemicals) to raise the level of free chlorine in the pool. When your free chlorine levels are too low, bacteria, algae, and chloramines begin to overwhelm your pool and make it unsanitary. Shocking your pool consistently will ensure that you have the right amount of chlorine you need to keep your pool and family safe.

The typical chlorine scent you associate with pools happens when the chlorine is combined with the nitrogen in oils, sweat, urine, and other bodily fluids. A potent chlorine smell usually means that the water has been improperly treated, and a pool without a strong chemical scent is generally healthy.

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

Also known as cal hypo, this chemical is one of the more affordable and practical options when it comes to shocking your pool. You can usually find calcium hypochlorite at the pool or hardware store in a granular condition. This type of shock needs to be dissolved in water before you add it to the pool. I would recommend using this product at dusk as UV rays can interfere with the process. And as a plus, you can sleep off the 8-hour wait before you can safely enter the pool again. One last note on cal hypo – this shock won’t affect your pool’s cyanuric acid level.

Lithium Hypochlorite

While cal hypo will add extra calcium to the water, lithium hypochlorite (liquid chlorine) will not. For this and other reasons, it is much more expensive. It dissolves more efficiently, but in reality, you won’t even need to dissolve it beforehand. You can add it directly to the pool water since it’s already in liquid form. Like cal hypo, you should add the shock at night and wait at least eight hours before reentering the pool.


Out of the three main types of pool shock, dichlor is the easiest and safest to use. Dichlor (also known as sodium dichlor) is a granular pool shock and usually contains between 50-60% chlorine. 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. Just like the other two mentioned products, dichlor must also be used after dark and sit for at least 8 hours.

What About Non-Chlorine Shock?

Another option that you can use is non-chlorine shock. For more information on how to use it, please check out my guide on non-chlorine shock.

Why You Need to Shock Your Pool

Chlorine’s use in swimming pools is a double-edged sword. Pool chlorine is designed to eliminate any dangerous bacteria in the water, making it safe for humans to swim in. But it will also attach itself to ammonia in the pool, which can produce dangerous chemicals called chloramines. Depending on the number of people who use your swimming pool, the chlorine levels will fluctuate.

Ammonia is a product of sweat, urine, fertilizers, sunscreen lotions, bird droppings, and other contaminants that find their way into the pool. If you want a clean pool, you must break the chlorine bond (chloramine) by shocking it.

When to Shock Your Pool and How Often

Shocking your pool is not a one-time thing. It should be a regular part of your swimming pool maintenance routine. I recommend keeping a record or logbook near your pool to stay on top of this maintenance.

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

So what are some specific circumstances when you must shock the pool?

Rain and thunderstorms can contaminate the water with debris, dust, and excess rainwater. This is why you should always shock your pool after rain.

Algae outbreaks are also a key signal for pool shocking. When algae begin to appear, you should utilize a shock type with more chlorination to kill and remove the algae.

Pool parties of heavy pool use can introduce a lot of new contaminants to your pool water. You may want to shock your pool right after a big event.

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, shocking the pool will eliminate bacteria and make the water nice and clear.

How to Shock a Saltwater Pool

First off, it’s perfectly okay to shock a saltwater pool. All saltwater pools contain chlorine, it’s just being generated by the filter system and doesn’t need to be manually added to the pool.

So, you can use pretty much the exact same process I outlined above to shock your saltwater pool. However, I recommend that you stick with dichlor or non-chlorine shock.

Get My Free Pool Care Checklist

Download my free, printable pool maintenance checklist to help you accomplish regular pool care tasks for any type of swimming pool.

Something went wrong. Please check your entries and try again.

Pool Shock Safety Tips

When cleaning your pool, you will be in constant contact with hazardous chemicals, so it is important to follow the necessary safety precautions. Check the labels on your shock products to ensure proper storage. Pool shock can cause chemical burns on the skin and damage your eyes. For this reason, it is extremely important to wear protective equipment when handling the chemicals. Gloves and eyeglasses are absolute necessities, but you should also wear long sleeves and pants to prevent contact with your skin.

Be sure to wait the necessary time before allowing anyone into the water (about 24 hours). The chemical balance in the pool must be optimal before swimmers hop in.

Wrapping Up

Although not too complicated, there is a process to follow when shocking your pool. 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! You must decide on a quality pool shock product or two that fits your needs and then nail down a consistent pool maintenance schedule.

Questions? Shoot me a note and I’ll be happy to help.

Scroll to Top