Pool chlorine calculator
How much chlorine to add to raise free chlorine, for liquid chlorine, cal-hypo, dichlor or trichlor. Enter your CYA and we'll suggest the target too.
Pour in front of a return with the pump running. Retest after 30 minutes. Never mix chlorine products with each other or with acid.
How it works
Each product has a standard strength: the amount it takes to raise 10,000 gallons by 1 ppm. The calculator multiplies that by how many ppm you need and by your gallons / 10,000.
The suggested target comes from your CYA: about 11.5% of CYA, never below 3 ppm. Dichlor adds about 0.9 ppm of CYA and trichlor about 0.6 ppm for every 1 ppm of chlorine; cal-hypo adds about 0.7 ppm of calcium.
Questions
What should my free chlorine be?
It depends on your CYA (stabilizer). Chlorine gets weaker as CYA goes up, so a common rule is to keep free chlorine at about 7.5% of CYA as a minimum and around 11% as a target. At 50 ppm CYA that's a minimum near 4 and a target near 6.
How much liquid chlorine raises 10,000 gallons by 1 ppm?
About 10.7 fl oz of 12.5% liquid chlorine, or 12.8 fl oz of 10% liquid chlorine.
Does the chlorine type matter?
Yes. Dichlor and trichlor add CYA every time you use them, and cal-hypo adds calcium. Liquid chlorine adds neither, which is why most pool pros use it for daily dosing.
Is this a shock calculation?
It works for any raise in free chlorine. For a full shock (SLAM), the target is usually about 40% of your CYA; enter that as the target.
Run this math on every stop.
ShockRoute does the dosing for each pool's gallons in the tech app, logs it, and prices it from your supply costs. Free up to 25 pools.