The generic answer you'll find everywhere is "once a week." And for some pools in some climates, that's exactly right. But for others it's overkill, and for others it's not nearly enough. Here's how to figure out what your pool actually needs.
Shocking raises your free chlorine to a level high enough to destroy chloramines (the byproduct of chlorine doing its job), kill bacteria, and wipe out early-stage algae. It's essentially a reset for your water chemistry.
Regular chlorine maintains your pool. Shock treatments fix it.
If you're in a hot, sunny area, UV rays destroy free chlorine rapidly — sometimes within hours. Algae thrives in warm water. You should be shocking once a week as a baseline, and potentially twice a week during peak summer heat.
Every 1-2 weeks is typically sufficient. Shock after heavy rain, heavy use, or any time the water looks off.
If your pool doesn't get heavy use and temperatures are mild, shocking every 2 weeks may be enough. Always test before deciding — your chlorine levels will tell you.
Salt cells generate chlorine continuously, so you need to shock less often than a traditional chlorine pool. Monthly shocking is usually sufficient unless you've had heavy use, algae, or a storm.
💡 The real answer: Shock when your combined chlorine (chloramines) gets above 0.5 ppm, or when free chlorine drops below 1 ppm and won't hold. Testing is more reliable than a fixed schedule.
Always shock at dusk or after dark. Sunlight burns off unstabilized chlorine (the kind in most shock products) extremely quickly — you can lose up to 50% within an hour in direct sun. Shocking at night gives it time to work through the water before sunrise.
⚠️ Don't swim for at least 8 hours after shocking, or until free chlorine drops back below 3 ppm. Test before anyone gets in.
For a standard maintenance shock, use 1 lb of cal-hypo shock per 10,000 gallons. For a more aggressive treatment (cloudy water, algae threat), double it to 2 lbs per 10,000 gallons.
PoolBoy tracks your climate, pool size, and water type to remind you when to shock — and tells you exactly how much to use.
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