How-To Guides | Spa Shock & Why You Need It

The majority of water problems we hear about can be easily solved with shocking compounds. We'll explain the different recommended types and the right way to use them.

What is Shock Treatment?

Shocking a spa means applying an ample dose of chlorine (sodium dichlor) or non-chlorine shock (potassium monopersulfate or MPS). One purpose of this treatment is to break down organic waste contaminants that cause odor and cloudy water. After treatment, water quality and clarity are often completely restored.

If irritating chloramines are present, shocking also converts them back to active chlorine. In bromine spas, shocking converts the bromide ion (which by itself has no disinfecting capability) to hypobromous acid in water, a good sanitizer. Both of these shocking products are 100% compatible with the alternative sanitizer systems that we offer.

Regardless of which sanitizer system you use, periodic shocking is essential for clear, clean hot tub water. It also allows your sanitizer to perform at peak efficiency.

Note: These products are not compatible with biguanides such as Baqua® which we do not support.

Non-Chlorine Shock - regular use for maintenance

Non-chlorine shock is monopersulfate compound, often called MPS for short. It is an oxygen-based shock, preferred by many because it has little or no odor.

Our OxySpa non-chlorine shock is 100% compatible with chlorine, bromine, Nature2, Frog products, and dichlor shock. It is the ideal primary shock to use with these products regularly.

Although not classified as a sanitizer, non-chlorine shock does oxidize contaminants and greatly improves water quality and clarity.

Dichlor Shock - occasional use to clear up problems

Dichlor shock is a form of chlorine often called sodium dichlor. Technically it's both a sanitizer and a shock, although we do not recommend chlorine as a primary sanitizer in spas.

Dichlor is 100% compatible with bromine, Nature2 and Frog products, as well as non-chlorine shock. It's recommended as a startup shock with these products, and also for quick water problem correction.

Shocking with dichlor is a fast, easy way to clear up many problems like musty odor, cloudiness, and slimy water.

Note: Always pre-dissolve dichlor in water before adding it to the spa to avoid damage to acrylic or vinyl surfaces.

When to Shock

It's good practice to shock with dichlor when you refill your spa. After that, regular maintenance can normally be accomplished with non-chlorine shock.

Other times for shock treatment include before or after heavy use and when the spa has been neglected. Whenever a dose of non-chlorine shock needs an extra boost, dichlor will usually provide it and clear up problems.

Read more about the decontamination method for hot tubs with severe, persistent water quality issues.

With Alternative Water Purifiers

Many people have switched to alternative purification systems such as Nature2 or Spa Frog to get away from chlorine. It is still a good idea to start these systems with a dose of dichlor.

Shocking with dichlor ensures a clean start and will help curb problems from pre-existing contaminants. Dichlor is also the quickest way to fix problems after a heavy bather load.

If you don't like chlorine, don't despair. Remember that with the cover open, jets running, or exposure to sunlight, that occasional chlorine dose dissipates fairly quickly.

With alternative sanitizers, OxySpa non-chlorine shock is your go-to shock. In many cases, dichlor is rarely used after the startup dose.


The amount of shock to use will depend on the bather load, and which water sanitization system you have chosen. Refer to our Preparation & Maintenance Guide and read all product package directions for more information.


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Little Rock AFB, AR

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