Using Pool Shock in Your Pool Maintenance Program

Pool shock is an important part of any swimming pool maintenance program. “Shocking” your pool simply means that you are giving it a large dose of chlorine all at once to sanitize the water quickly. Pool shock consists of un-stabilized pool chlorine, whereas the chlorine you use on a daily basis (usually through the application of slow-dissolving chlorine tablets or sticks or granular chlorine) is stabilized. Your pool’s chlorine levels will be high for about 24 hours after application.

Pool shock helps you get rid of chloramine, the chlorine that has worked to kill algae or bacteria and has now become ineffective, in your pool. Chloramine in your swimming pool causes a strong chlorine odor and burning eyes when swimming, and prevents Free Available Chlorine, the chlorine that still has sanitizing abilities, from doing its job. If you haven’t used pool shock regularly and don’t know how much chloramine is in your pool water, use a chlorine test kit that provides readings on Total Available Chlorine, which is the amount of Free Available Chlorine plus the amount of chloramine.

If you close your pool for the winter, it’s important to use pool shock when you re-open the pool in spring; for maintenance, use pool shock once per week throughout the season. Use a four-way shock that kills bacteria, controls algae, destroys organic contaminants, and oxidizes to create crystal-clear, sparkling pool water.

The amount of pool shock you need to use is determined by your pool’s size. If you are confused about how much to use, call your pool supply store for help. The best time to use swimming pool shock is in the late afternoon or early evening. Run your pool equipment for at least one hour after shocking to help control algae growth.

Pool shock treatments are also used when certain undesirable conditions exist in your pool. Because there can be more than one cause for each of these conditions, consult a pool care expert if you aren’t sure of the cause before shocking your pool.

• Possible Cause: Excess organic waste
• Solution Once Cause is Confirmed: Shock your pool with one pound of shock per 10,000 gallons of pool water.

• Possible Cause: Green algae growth, a free-floating variety which gives water a cloudy green color. This type of algae growth is easy to correct if treated early.
• Solution Once Cause is Confirmed: Shock pool and follow with an algaecide.

• Possible Problem: Mustard algae
• Solution Once Cause is Confirmed: Shock pool and follow with an algaecide that kills yellow algae.

• Possible Cause: Excessive organic wastes
• Solution Once Cause is Confirmed: Shock pool with one pound of shock per 10,000 gallons of pool water.