4 Things to Know About Shocking a Pool With Calcium Hypochlorite

Use calcium hypochlorite or liquid chlorine, not dichlor or trichlor Dichlor and trichlor add more cyanuric acid (stabilizer), which makes chloramine problems worse. Cal-hypo or sodium hypochlorite provide unstabilized chlorine that actually breaks down chloramines.

Shock at 10 times the combined chlorine level If combined chlorine is 2.0 ppm, raise free chlorine to 20 ppm and hold it there. Use a DPD test kit, not test strips, since strips can’t measure that high accurately.

Run the pump continuously and brush the walls Keep the pump running 24/7 and brush all surfaces. Low cyanuric acid levels let sunlight help oxidize chloramines and eliminate the “pool smell.”

Drain and refill if cyanuric acid is over 100 ppm Conventional shocking won’t work with stabilizer that high. Partial draining is the only fix—otherwise you’re wasting chemicals.