Pool Shock Calculator: How Much Shock Does Your Pool Actually Need?
???? Recommended Products
*As an Amazon Associate, we earn from qualifying purchases. These are products we genuinely recommend for pool shocking.*
In The Swim Cal-Hypo Pool Shock 24-Pack (~$60) — This is the workhorse. Cal-Hypo shock at 73% available chlorine. Dissolves fast, works on all pool types, and keeps well in storage. A 24-pack lasts most pools an entire season.
Taylor K-2006 Complete Pool Test Kit (~$90) — You can’t use a shock calculator without accurate test results. This kit measures free chlorine, pH, alkalinity, calcium hardness, and cyanuric acid with lab-grade reagents. Test strips are fine for quick checks, but this is the gold standard when dosing matters.
DryTec Calcium Hypochlorite Pool Shock 24-Pack (~$65) — Alternative to In The Swim. Same Cal-Hypo formula, 68% available chlorine. Some pool owners prefer DryTec’s packaging (resealable bags reduce clumping).
In The Swim Non-Chlorine Pool Shock 6-Pack (~$35) — For oxidizing contaminants without raising chlorine. Perfect for salt water pools or if you’re already at high chlorine and just need to clear cloudy water. No wait time to swim after treatment.
AquaChek 7-Way Pool Test Strips (100 count) (~$17) — Convenient for quick daily checks. Tests free chlorine, pH, total alkalinity, stabilizer, total hardness, and more. Use these for routine monitoring and switch to the Taylor kit when you need precision dosing.
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???? Calculate It Instantly with Pool Chemical Calculator
Stop guessing with your pool chemistry! The Pool Chemical Calculator app tells you exactly how much shock to add based on your pool’s size, current chlorine level, and what you’re treating.
✅ Cal-Hypo, Dichlor, Lithium, Liquid & Non-Chlorine shock supported
✅ Works for all pool types — chlorine, salt water, above ground
✅ Calculates chlorine, pH, alkalinity, calcium hardness & more
✅ Free to download
Download for Android →
Download for iPhone/iPad →
Use Online →
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Frequently Asked Questions
How much shock do I need for a 20,000 gallon pool?
It depends on your current chlorine level and what you’re treating. For routine maintenance (raising from 2 ppm to 10 ppm), a 20,000-gallon pool needs about 1.5 pounds of Cal-Hypo shock. For algae treatment (raising to 30 ppm), you’d need closer to 5 pounds. A pool shock calculator gives you the exact amount based on your situation.
Can I use a shock calculator for liquid chlorine?
Yes. Liquid chlorine (sodium hypochlorite) is typically 10-12.5% available chlorine. Most shock calculators let you select liquid chlorine as your shock type and adjust the dosage accordingly. Liquid chlorine is gentler on pool surfaces but requires larger volumes (gallons instead of pounds).
How long after shocking can I swim?
For chlorine-based shock (Cal-Hypo, Dichlor, Lithium), wait until chlorine drops below 5 ppm — usually 8-24 hours. For non-chlorine shock (potassium peroxymonosulfate), you can swim in as little as 15 minutes. Always test before swimming.
Do I need to shock my pool if I use a salt water system?
Yes. Salt water chlorine generators produce chlorine continuously, but they don’t produce enough to handle heavy use, rainstorms, or algae outbreaks. Shocking supplements the generator. A shock calculator helps you avoid overdoing it, since your baseline chlorine is already stable.
What’s the difference between shock and regular chlorine?
Shock is *highly concentrated* chlorine (or non-chlorine oxidizer) designed to quickly raise chlorine levels or oxidize contaminants. Regular chlorine (tablets, granules) is for daily maintenance. Shock is a temporary spike; regular chlorine is a slow release. You need both.
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Final Thoughts
A pool shock calculator isn’t a gimmick. It’s a tool that saves you money (by preventing overdosing), saves you time (by preventing underdosing), and keeps your pool chemistry predictable. Whether you’re shocking weekly for maintenance or battling a green pool, knowing *exactly* how much to add is the difference between “this worked” and “why is my pool still cloudy?”
Your pool’s size, your current chlorine level, the type of shock you’re using, and what you’re trying to fix all matter. A calculator accounts for all of it. Your eyeball and the generic bag instructions don’t.
Download a pool chemical calculator app (or use an online one), punch in your numbers, and stop guessing. Your pool — and your wallet — will thank you.
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