The goal in shocking your swimming pool or hot tub is to ultra-chlorinate the water, kill off the chloramines, and rid bacteria from floating around. The most important times to do so are in the beginning of the swimming season and after high amounts of activity, like a pool party. This article describes how to shock your swimming pool, and provides considerations on which shock to choose.
To keep your swimming pool healthy and pleasant, shocking your pool should be apart of your weekly or bi-weekly maintenance. Keeping up on this regular maintenance will avoid algae and bacteria build-up, ultimately saving you from cloudy water. There are many liquid pool shock kits that claim to get the job done. Some may advertise to clear your pool in one sitting, but before you decide to invest in a liquid pool shock kit, there are chemistry basics in the mix you need to know.
As mentioned before, shocking your pool should be apart of your weekly maintenance. Even if the water looks crystal clear, it is not an accurate indication of chemical balance within the swimming pool/hot tub. Whether the bacteria is man-made or the chlorine is diluted from natural causes, your pool will need help in staying clean and clear. High activity in your pool releases sweat, makeup, and other humanly bacteria, and needs to be combated with high amounts of chlorine. When it comes to issues that can be tied to nature, watch out for days with heavy rainfall and days with lots of sunshine. During hot summer days, the sun breaks down the chlorine in your pool by 5ppm per day. Just as the sunshine causes you to lose free chlorine, rainy days also dilute the amount of chlorine in your pool.
When your free chlorine level drops below 3ppm, it’s a good time for you to shock your pool. If you want to know more about the differences between free chlorine, total chlorine, and combined chlorine, check out our blog post here: What is Free Chlorine, Combined Chlorine, and Total Chlorine?
Cal-Hypo Shock is like a bottom shelf liquor- it’s cheap and it’s strong. This type of pool shock kit usually comes in a granular form. It needs to be mixed in a bucket with warm water before it enters your pool.
“The free chlorine generated from calcium hypochlorite helps provide clear water by killing algae and by destroying organic matter that will cloud the water if allowed to build up. Chloramines, the most common cause of unpleasant odors, are also eliminated by the action of free chlorine.”
-Association of Pool and Spa Professionals
https://www.apsp.org/Portals/0/RWQ%20Fact%20Sheets/Calcium%20Hypochlorite%20-%20July%2029,%202014.pdf
Because Cal-Hypo Shock dissolves quickly, it’s cleaning power is somewhat on a timeline. While this type of pool shock kit is very strong, it’s also the most sensitive to sunlight. To maximize the effects of Calcium Hypochlorite, avoid application in direct sunlight.
Like Calcium Hypochlorite, Di-Chlor is also a granular pool shock kit. Unlike Cal-Hypo Shock though, Sodium Dichlor is a slow dissolving mix, which maximizes and extends the cleaning power. It contains a balanced pH level and holds zero amounts of calcium, which means it increase the “hardness” of your pool water. Be conscious of the effects to the cyanuric acid levels in your pool. While the lack of calcium may help with pool hardness, using Sodium Dichlor as a pool shock can cause Cyanuric Acid levels to rise.
Lithium Hypochlorite is a type of liquid pool shock. Liquid shock kits like this one will save you time in your maintenance schedule. One must take note that Lithium Hypochlorite doesn’t contain any calcium in itself. If your pool has high calcium indications, this may be the liquid pool shock kit for you.
“Its primary pesticidal use is to control algae, bacteria and mildew in swimming pool water systems, hot tubs and spas…”
-EPA
https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-014702_1-Dec-93.pdf .
Safer for vinyl-lined pools, Potassium Peroxymonosulfate is a salt-based oxidizer. Because there is no chlorine content in this pool shock kit, it doesn’t kill bacteria. Instead, it oxidizes the organic matter in the pool. Non-chlorine shock works by killing the dead chlorine (chloramines) and allows the remaining free chlorine to attack algae and bacteria. While non-chlorine shock kits obtain lesser cleaning power, they are a safer alternative to using chlorine.
Try out our Pool Calculator as you clean and maintain your pool! For more information on how to care for your swimming pool, see our blogs on Pool Maintenance
Want to learn more about algaecide? Read on to find out when to add algaecide to your pool maintenance routine and other helpful tips.
In this quick guide, we’ll answer the question “can you over shock a pool” and unveil the factors to consider when shocking a pool.
Maintaining both pH and total alkalinity in your swimming pool is important for keeping your pool properly sanitized and non-corrosive. Total alkalinity is to pH what cyanuric acid is to free chlorine. Total alkalinity stabilizes pH levels. The ideal pool pH level is 7.4 to 7.6. The ideal total alkalinity level is 80 to 120 ppm.
The Association of Pool and Spa Professionals recommends free chlorine levels for both swimming pools and hot tubs be kept between 2.0 and 4.0 ppm. However, the Center for Disease Control recommends free chlorine stay above 1 ppm in pools and 3 ppm in hot tubs.