Chemical “shock” products have become seen as a cure-all for many pool conditions, even though they have a limited and specific purpose. Pool owners should only use shock in instances where it will actually help. Knowing exactly what shock is and how it works will aid in making this decision.

What Exactly Is Pool Shock?

“Shock” refers to a variety of oxidizing products that fall into two broad categories: chlorine and non-chlorine.

A chlorine-based shock is sometimes called a “hyper-chlorination” product. Hyper-chlorinate shocks work like a super-powered version of the granular chlorine you would normally add to your pool, but with the benefit of extra oxidation power.

Non-chlorine shocks are usually made from potassium monopersulfate or a similar compound. These products are designed to exclusively provide oxidation power to the water, and they do not sanitize like a regular chlorine product would.

What is Oxidizing?

Oxidation is a chemical reaction where electrons are stripped from a molecule or compound. Most compounds affected by this reaction break down or become dissolved. A classic example of oxidation is something made of iron metal becoming rusted. Rust forms when oxygen takes away electrons from then combines with the iron, forming iron oxide.

In pools, oxidation is part of the chemical reactions that occur when you add chlorine to your water. Most of the chlorine will break down in the water to form hypochlorous acid. This chemical is what actively kills the unwanted algae and bacteria.

When organic compounds like sweat, suntan lotion or leaves enter the pool, the chlorine will combine with these organics instead and form chlorinates. With enough organic matter in your pool, all of your chlorine will go towards making chlorinates instead of hypochlorous acid. When this happens, algae and bacteria levels will go up despite your adding of chlorine on a regular basis.

Why and When Should I Oxidize?

You should use an oxidizing shock product when your regular dose of chlorine is not working. A common sign is that the water is becoming cloudy or green.

Measuring the pool’s chemistry is the only surefire way to test to see if chlorine is working properly. Most measurement tools will have “Free Chlorine” and “Total Chlorine” amounts. Free chlorine is hypochlorous acid that is available to kill pathogens; total chlorine is all chlorine, including undissolved chlorine granules and chlorinates formed from organic compounds.

If your total chlorine is way higher than your free chlorine, it means your chemicals are having trouble keeping up with the pathogens and organics in the pool. This scenario is when you should use shock.

The Best Way to Use Shock

Decide on the product you want. Hyper-chlorinated shocks will work alongside your chlorine, sanitizing pathogens and helping oxidize organics in the pool. You will have to wait at least twelve hours for your chlorine levels to become low enough to swim in the pool again.

Non-chlorine shock products only oxidize. They will not help the chlorine sanitize. You should use these when you do not suspect an algae or bacteria problem, but think that your chlorine is struggling with too many organics.

Both products should be added around night-time when the sunlight will not destroy the active chemicals.

Here is a step-by-step for adding shock to your pool:

Determine how much shock you will need.  Calculate the ppm levels your free chlorine needs to be at for the pool to be balanced again. One ounce of shock should generally be used for every 7,500 gallons of water to raise the ppm by one.

Dissolve the shock granules or liquid in a large bucket of water before using. Always add product to water, not the other way around. Use appropriate safety gear like nitrile gloves, protective goggles and clothes you would not mind having bleach splashed on.

Dump the dissolved shock into the pool slowly without splashing. Make sure you pour it all along the perimeter.

Run the pump for at least eight hours afterward. You may also want to vacuum the pool and clean/backwash the filter when you are done; most of the oxidized organic compounds will sink to the bottom.

With proper pool care, you should never have to shock your pool again. If you are having difficulty keeping up with the right amount of chemicals, consider hiring a professional Boca Raton pool service. We can help you maintain a good balance and clear water. Visit our pool maintenance page for more details.