Pool Shock Calculator
How much shock to add to lift your free chlorine up to shock level — from your pool volume, current reading, and the strength printed on your product.
Add about
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Estimate only — always follow the dosing instructions on the product packaging and never mix chemicals.
Track it automatically with Algae Later →What level should shock reach?
Routine shocking lifts free chlorine to around 10 ppmto burn off chloramines and kill off early algae. A visibly green pool needs more — often several rounds — and stays cloudy until the chlorine has done its work. Don't swim until free chlorine has fallen back to the normal 1–3 ppm range.
Frequently asked
- How much shock does a green pool need?
- More than a routine shock — a green pool often needs a higher target (15 ppm or more) and repeat doses over a day or two until the water clears and holds chlorine. Enter a higher target above and re-shock after re-testing.
- When can I swim after shocking?
- Wait until free chlorine drops back to 1–3 ppm. That's usually several hours to overnight depending on sun and dose — always re-test before getting in.
- Should I fix pH before shocking?
- Yes — balance pH into the 7.2–7.6 range first. Chlorine is far more effective at correct pH, so your shock goes further.
- How often should I shock?
- Shock after heavy use, parties, heat waves or heavy rain, or whenever combined chlorine climbs. Regular testing every 2–3 days tells you when it's needed.