Chlorine
WHAT IS IT: Disinfectant/Sanitizer available in tablets, sticks, granules, and liquid form.
WHAT DOES IT DO: Kills bacteria, Sanitizes the water
LOW CHLORINE: not effectively kill bacteria
HIGH CHLORINE: corrosive, itchy skin, watery eyes
FREE CHLORINE - Chlorine molecules available to clean and sanitize the water (1-3 ppm)
COMBINED CHLORINE - Chlorine molecules attached to dirt and started cleaning.
TOTAL CHLORINE - Free Chlorine + Combined Chlorine
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FREE CHLORINE OR TOTAL CHLORINE?
FREE CHLORINE - Chlorine molecules available to clean and sanitize the water (1-3 ppm)
COMBINED CHLORINE - Chlorine molecules attached to dirt and started cleaning.
TOTAL CHLORINE - Free Chlorine + Combined Chlorine
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Once chlorine has completed the hard work of sanitizing and preventing algae, it will combine with other waste material in the pool. It combines and forms chloramines. When you get in a pool and smell 'chlorine', most of us think it is because there is too much chlorine in the water. Actually, what you smell is chloramines. Time to shock!
CHLORINE Cleans by Disinfecting, Sterilizing and Sanitizing.
Chlorine works by a chemical reaction. Chlorine attaches to dirt (combined chlorine) and make chloramines. Chloramines stay in the water until they are oxidized by shock. If you shocked and still have combined chlorine, you either did not add enough or something in the water (algae) is using all of the chlorine.
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CHLORINE DEMAND: Amount of chlorine needed to clean all organic matter in the pool
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SUPERCHLORINATION: Adding larger doses to eliminate all combined chlorine
CHLORINE BREAK POINT: amount of chlorine required to destroy all combined chlorine in water (add chlorine amount equivalent to 10x amount of combined. Also called breakpoint chlorination.
CHLORINE COMPOUNDS
Not all chlorines are compatible. In fact, mixing different types of chlorine can be extremely volatile and even lethal. For example, calcium hypochlorite (cal-hypo) and liquid bleach can combust into flames when mixed.
DICHLOR 10ppm chlorine + 9ppm CYA
TRICHLOR 10ppm chlorine + 6ppm CYA
SODIUM HYPO Liquid Chlorine Very high pH
When you shock your pool, you are changing these amounts, or you are trying to. After shocking pool water, the free chlorine level will be high immediately after. Total chlorine should be getting closer to the free chlorine amounts because the shock is sanitizing away all of the chloramines; the product of combined chlorine. Combined chlorine is chlorine attached to dirt and started cleaning. These turn into Chloramines. If you have ever smelled chlorine in a pool, thinking wow, that is strong so there must be too much, well, it is exactly the opposite. What you smell is the chloramines, which means there is a lot of combined chlorine in the pool and it is time to shock!
CHLORAMINES: product of combined chlorine, the chlorine smell in a pool is usually chloramines, not over chlorination
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HOW TO SHOCK A POOL
Clean the pool of all debris; you can easily use a net to get the big organic tree leaves out, but it will be harder to get the algae out. Shock should be attacking the algae and not the leaves in the pool.
Adjust pH to 7.2 for best results. Chlorine works better and is more effective at a lower pH
When shocking to restart your chlorine (removing chloramines aka combined chlorine), you want to get Free Chlorine level to at least 10 times the combined chlorine level.
If you are shocking to kill algae, get Free Chlorine level to 30 ppm
Make sure you are using enough. It can be scary adding a huge amount of chlorine/shock to pool, but it will get back to a normal level!
For powdered shock, pour into a bucket and stir before adding to pool. For optimal dispersion, walk around outside of pool and pour in slowly. If you pour it in one place, you will bleach the liner and end up with white spots.
Keep pump on for at least 8 hours and keep uncovered. Covering may impede the circulation and you do not want that when you are shocking the pool.
Because Circulation of the pool shock and filtration is so important during the shock process, it is best to backwash before and after, or clean the filter before and after also
After about 8-12 hours, if chlorine levels are still at zero, shock the pool again. (This means all of the chlorine was used killing algae/bacteria in the pool.)
Because the sun's UV can burn off chlorine, the best time to shock is when the sun goes down.
If you have Algae, after chlorine levels come back down vacuum and then scrub with brush and vacuum again. This may be dependent of circulation and how bad the algae bloom was when you started.
pH too high = chlorine doesn’t work = Algae / pH must be 7.2–7.4 for shock to work
Pool shock will deactivate algaecide so use algaecide AFTER shocking (as preventative) once the free chlorine level has come back down to normal range between 1-3 ppm.
Run the filter 24/7
