Why does this shock calculator ask for CYA?
CYA changes the free chlorine level needed for a real shock. The calculator uses your CYA reading to choose a shock target instead of assuming one bag per 10,000 gallons.
Free Pool Tool | Ellis County, TX
Pool Shock Calculator
Shock based on your CYA level, not a one-bag-per-10,000-gallons label rule.
Calculator
Enter your pool numbers
Fractions like 1/4 or 1/8 work in number fields. Results are planning estimates, not a binding service diagnosis.
Result
321 oz Liquid chlorine 12.5%
Based on 40 ppm CYA, the planning shock target is 16 ppm FC.
Shock target16 ppm FC
Pounds20.06 lb
Pro Take
You can do this yourself. Or you can stop chasing it.
If the pool is already green enough that you cannot see the bottom, one shock dose may waste money. A&M can turn a green pool around with a real process.
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How to test
Get the reading before you dose
Use FAS-DPD for high chlorine readings and a CYA turbidity test before shocking.
- Shock at dusk or after dark when possible.
- Pre-dissolve granular shock in a clean bucket of pool water.
- Keep the pump running and retest before swimming.
Companion Guide
When and How to Shock Your Pool
Read the paired blog post for the plain-English version of the chemistry, testing, and common homeowner mistakes.
Read the guideFAQ
Pool Shock Calculator FAQs
What if my current free chlorine is already near the shock target?
The calculator only doses the gap between current free chlorine and the CYA-based shock target. If you are already close, the recommended amount will be much smaller.
Which shock product should I choose in the calculator?
Choose the product you will actually add: liquid chlorine, cal-hypo, or dichlor. Cal-hypo adds calcium and dichlor adds CYA, so product choice affects more than just the ounce count.