Pool shock is a granular pool chemical, which should be added to your swimming pool at least once each week. You should shock more frequently if the pool is used heavily, after you receive large amounts of rain, or during extended periods of hot, sunny weather. The chlorine tablets or granular chlorine that you constantly dissolve into your pool water seeks out and combines with bacteria and other organics on a molecular level, to neutralize these harmful contaminants. In the process of killing these harmful contaminants the chlorine becomes inactive, and the chlorine and bacteria that have combined together is called "Combined Chlorine". The combined chlorine must be removed from the swimming pool to keep your pool water safe and clean. The combined chlorine is removed by "Shocking" the swimming pool. Super chlorinating or "Shocking" means drastically raising the chlorine level of the swimming pool for a short time, to a high enough level that the combined chlorine is oxidized and burnt off.

There seems to be a very wide selection of swimming pool shock on the market, and each pool supply distributor works hard to make their product seem a step above the rest. When all of the products are compared side by the side, the only real difference on the labels is the concentration of the active ingredients in the product. The standard pool shock that most pool owners use has the active ingredient Calcium Hypochlorite. You should expect the label to read 65% Calcium Hypochlorite. Another more concentrated version of the pool shock may have as much as 75% Calcium Hypochlorite. Some manufacturers advertise a Calcium Hypochlorite based shock product, which allows you to swim in the pool shortly after adding it. Upon examining the label you will notice that the concentration of Calcium Hypochlorite is only around 47%. Although you can swim shortly after using this type of shock product, the lower concentration of Calcium Hypochlorite may not be enough to effectively destroy bacteria and harmful contaminants in your pool.

Always add shock to water not water to shock. Wear clothes you don't care about cause they might get bleached. Warm water dissolves shock faster than cold, its your choice. Use a wooden stick and stir around the shock making sure it gets all dissolved or as much as your can. Pour the bucket of shock all around your pool or heave some in the middle. You may have some undissolved shock at the bottom of your bucket. In this case just dip your bucket in some pool water give it a swish around and pour it back into the pool to help dissolve some of that shock.

Most shocks require at least 8 hours with no one in the pool read the label before adding shock. Also some dealers will tell you to add shock directly to your skimmer. This is not a good idea especially if you have chlorine or an automatic chlorinator. Reason being is because calcium hypo and tri-chlor, which can be found in chlorine tablets, creates a harmful chlorine gas. To get to the point, your automatic chlorinator could explode. It's happened.

Another type of shock that is widely available at any local pool store, hardware store and many grocery stores is liquid chlorine. This liquid chlorine is commonly used as shock, and used in place of chlorine tablets. Many pool owners believe this liquid chlorine is all they need to properly maintain a swimming pool, and unfortunately this is incorrect. Liquid chlorine is very inefficient and costly compared to properly maintaining a swimming pool using chlorine tablets and a weekly shock treatment. Liquid shock may seem easier to use than the granular shock for some pool owners because you simply walk up to the pool and dump the liquid in. The problem is that after you dump the hazardous liquid in your pool, you have to dispose of all the empty plastic bottles with the dangerous chemical residue inside. Granular pool shock is packaged in small, easy to use 1 lb. bags. If any children have access to the area where pool chemicals are stored it will be far easier to have an accident involving full or empty bottles of liquid chlorine, than an accident with bags of granular pool shock.