04/19/2026
🚨WHEN SHOULD YOU “SHOCK” THE POOL?🚨
“Shock” (super chlorination) isn’t something you do on a schedule—it’s something you do as needed, even on salt pools. Some pools rarely need it, others might need it weekly depending on what the pool goes through. It doesn’t hurt to give a little “POW” once a week, but not always necessary.
The real key is maintaining proper chlorine levels daily. A good rule of thumb is to keep your free chlorine at about 7.5% of your CYA (stabilizer). If you fall below that, algae can start multiplying faster than chlorine can kill it—and that’s when you may need to super chlorinate to catch back up and oxidize what got ahead.
Situations where super chlorinating is needed:
* Heavy swimmer load
* Big rainstorms
* Something nasty in the pool (like a dead animal)
* After adding products that temporarily drop chlorine (like stain treatments)
If there’s a f***l or bio accident, there are specific chlorine levels that must be reached and held for a certain amount of time to properly kill pathogens. Refer to ADA Recommendations.
Now let’s talk about that strong “chlorine smell.” That’s not actually chlorine—it’s chloramines (combined chlorine) from partially oxidized stuff like sweat or, yeah… p*e.
This is where breakpoint chlorination comes in.
Old school rule:
👉 Raise free chlorine to 10× your combined chlorine
Example:
Little Timmy and drunk Uncle Eddie were in the pool for 4 hours. Neither one got out to use the restroom.
The next day you test:
* Free Chlorine (FC) = 2 ppm
* Total Chlorine (TC) = 3 ppm
That means:
* Combined Chlorine (CC) = 1 ppm
To destroy those chloramines:
* 10 × 1 ppm = 10 ppm target
* You already have 2 ppm → so you need to add 8 ppm more chlorine to achieve breakpoint chlorination.
That spike is what helps fully oxidize all that leftover contamination.
(And yes, that “10× rule” is a bit old school and not perfect science—but it usually gets you where you need to be.)
Some people argue that “shock” should only refer to breakpoint chlorination, but that’s mostly semantics. These days, most products labeled “shock” are just designed to super chlorinate, so the term gets used more loosely.
Bottom line:
If you keep your chlorine properly maintained daily, you won’t need to shock often—but when your pool gets behind or takes a hit, that’s when shock becomes necessary.
