Scale the dose on your bag
Your dose = label dose × your pool volume ÷ the pool volume on the label. Match the label’s treatment instructions to the condition you are treating; routine treatment and algae treatment may use different amounts.
For a label dose of 1 lb per 10,000 gallons, use 0.75 lb for 7,500 gallons, 1.5 lb for 15,000 gallons or 2 lb for 20,000 gallons. Weigh a partial bag instead of rounding up to a whole one.
Calculate a chosen chlorine increase
If your treatment calls for a specific free-chlorine level, enter your current test, target and product strength in the shock calculator. At 65% available chlorine, increasing 10,000 gallons from 1 to 10 ppm takes about 1.16 lb.
Test pH and stabilizer (CYA) as well as free chlorine before treating algae. Use the CDC procedure linked below for a fecal contamination incident; it specifies treatment levels and contact time.
Which product are you using?
| Product | Use this label information | Also check |
|---|---|---|
| Liquid chlorine | Bottle dose, reference gallons and stated chlorine increase | Storage age: liquid loses strength over time |
| Calcium hypochlorite granules | Dose by weight and available-chlorine percentage | Calcium hardness: this product raises it |
| Dichlor or trichlor | The specific product’s dosing directions | CYA: stabilized chlorine adds it; slow tablets have a different dosing schedule |
| Non-chlorine shock | Its own dose by pool size | This is an oxidizer rather than a free-chlorine dose |
When can you swim again?
Circulate for the time on the label, then test chlorine and pH. Swim once the readings meet that product’s re-entry limits. Retest before adding more because sunlight and contaminants consume chlorine.
If a test is off-scale, use a suitable-range test before deciding on another full dose.
Add, circulate, then retest
Follow the product label for application and mixing time, then retest before adding more. Keep chemicals separate: never mix chlorine with acid or other chemicals.
Common questions
How many bags of shock do I need for 15,000 gallons?
If the label’s applicable treatment dose is one 1 lb bag per 10,000 gallons, use 1.5 bags for 15,000 gallons. Different treatment directions or strengths can call for a different dose.
Should I use a full bag for a small pool?
Scale the label dose to your pool size and weigh the required amount. For a product dosed at 1 lb per 10,000 gallons, a 5,000-gallon pool takes half a pound.
Can I mix two shock products?
Keep them separate. Mixing different pool chemicals can cause a dangerous reaction; follow each product’s application instructions.
Sources & calculation notes
Check the original source for product-specific instructions and current details.
- Taylor: Complete kit instructions #5165, acid/base demand and treatment-table methodChecked 2026-10-27
- HASA: Sani-Clor safety data sheet, 2026 revisionChecked 2026-10-27
- CDC: Staying healthy in swimming poolsChecked 2026-10-27