If you have a home pool to care for, chances are you’ve heard of pool shock. It is an important step to help you maintain your stunning pebble pool finish and keep your pool water clean. Even so, you may be left wondering what pool shock is and how often you need to use it to keep your pool in tiptop shape. Not to worry, though! We’ve got your complete pool shock guide to help you keep your pool healthy and well-maintained.

What Is Pool Shock?
You’ve carefully chosen your perfect pebble pool finish from PebbleTec colors and lines. Now it’s time to learn how to care for it to keep it looking and feeling good as new! One very important step in your pool maintenance routine is regular shocking—but what does that mean, exactly?

Pool shock is an oxidizing chemical compound added to pool water to quickly raise the level of free chlorine, removing the dirt, bacteria, algae, and other contaminants that can damage your pebble pool finish and cause other problems. Increasing the amount of free chlorine to clean the water also helps remove combined chlorine—used chlorine that has lost its cleaning power.

Shocking your pool essentially provides a reset for the water. This applies to saltwater pools as well as chlorine pools—the main difference is that saltwater pools tend to require shocking less often than chlorine pools, which need the process to maintain steady chlorine levels.

There are three main types of pool shock:

• Calcium Hypochlorite (Cal Hypo): This is the most popular type of shock among pool owners for many reasons, namely its affordable price-point and low effect on other chemical levels—this makes rebalancing after shocking much simpler. Those with vinyl-lined pools will want to pre-dissolve this shock before adding it to the water to prevent bleaching and other damage to the pool surface.
• Sodium Hypochlorite: Most often used in a liquid form for pool care, sodium hypochlorite—or liquid chlorine—is essentially a stronger and purer form of bleach. Many pool owners opt for this form of shock because it is fast-acting and doesn’t leave behind a residue. Liquid chlorine can also be used in smaller amounts for daily pool care.
• Sodium Dichlor (Dichlor): This type of pool shock holds up to sunlight better than others, reducing the chances of a sun exposure-caused drop in chlorine levels. Dichlor is also a popular choice for pools without chlorine tablet cleaning systems, most notably saltwater pools or those with other mineral maintenance systems.
• Potassium Monopersulfate (Non-Chlorine Shock): Fast acting, less harsh than chlorine shock, and residue-free, non-chlorine shock is a great alternative for regular pool care. There are many benefits to using a non-chlorine shock. However, it’s important to note that the cleaning power isn’t as strong. While non-chlorine shock can handle most everyday pool care tasks, it may not be as effective in more severe cases of algae or bacteria contamination.

When to Shock Your Pool
Most pool experts suggest a shock schedule as frequently as once every week or two. However, your unique pool maintenance schedule will depend on a variety of factors.

• Algae: If you notice your pool water becoming murky or discolored, or you see residue settling on your pool surface, it may mean you have algae growing. Typical chlorine levels are often not enough to kill pool algae once it has begun to grow, making it necessary to shock your pool. It’s also important to note that some types of algae are chlorine resistant. If you are having difficulty removing algae from your pool, speak with a professional pool care specialist who can help you come up with a treatment plan.
• Heavy Use: Right after a big pool party is the perfect time to shock your pool. The introduction of bacteria, skin oils, and other factors can significantly reduce free chlorine levels, making a quick boost an important step to get your water back on track and prevent further issues from arising.
• Excessive Heat: Not only does sun exposure and high heat reduce the cleaning power of chlorine, but it also creates the perfect environment for bacteria to thrive. This makes it very important to shock your pool after periods of excessive heat or sunshine to prevent your pool water from getting murky.
• Rainfall: Rain plays a few roles in reducing the effectiveness of your pool’s chemical cleaning agents. First, rainwater can often bring with it unwanted contaminants. The introduction of pure water will also throw your pool’s pH levels out of balance and dilute the chemicals keeping the water clean. Rebalancing and shocking can help you prevent a little rain from becoming a big problem in your pool.
• Opening or Closing Your Pool: Shocking your pool is the last thing you should do before closing for the season and the first thing you should do upon reopening. This helps ensure the water is best prepped for easy cleaning, so you don’t have to spend more time and money than necessary to maintain your pool year-round.

Lastly, if your pool is giving off a heavy chlorine smell or your eyes and skin are irritated after swimming, it may be time to shock your pool. These are common indications that combined chlorine (chloramine) levels in your pool water are too high and need resetting.

Pool Shocking Tips
While pool shocking isn’t a difficult process, it can feel a bit overwhelming for first-timers. To ensure you know how to navigate the process and administer a successful pool shock, we’ve compiled a list of pool shocking tips.

• Balance your pool prior to shocking. That means a pH of 7.2-7.6, total alkalinity between 70-100 parts per million (PPM), and calcium hardness around 150-300 PPM—pH is the most important factor of the three in ensuring a successful shock.
• Shock your pool after the sun goes down. UV rays can cause the level of free chlorine in your pool to drop, reducing the effectiveness of shocking. However, non-chlorine shock can be used at any time of day without the risk of losing potency.
• Run your pool filter. Be sure to circulate your pool water for at least 8 hours after shocking. This helps ensure whatever contaminants the shock kills are removed from the water, rather than just floating around.
• Brush your pool surface. Whether you have a pebble pool surface, vinyl, or other, it’s important to brush after shocking. This can help distribute the chemicals around the pool evenly for a more effective clean.
• Avoid swimming for 24 hours. Yes, you read that right. Shocking your pool requires the introduction of a high dose of concentrated chemicals, so it’s important to wait a full 24 hours to get back in the pool after shocking with chlorine. This gives the chemicals time to settle so your pool water can return to a chemical balance that is safe for swimming. If you’re using a non-chlorine shock, though, you will be able to get back in the water after about 15 minutes.
• Aim for 30 PPM of chlorine. This is the chlorine level needed to remove algae, chloramines, and other pesky contaminants from the water. While the exact amount of shock you’ll need to achieve this depends on the type of shock you’re using, the ratio will typically sit between one to three pounds of shock—or one gallon of liquid chlorine—per 10,000 gallons of water. Severe cases may require additional shocking to fully sanitize the water.

Your pool water may turn a bit cloudy after adding the pool shock. This should settle as the chemical balance in your pool returns to normal.