How much chlorine to add to your pool
Your chlorine target is not a fixed number — it scales with your stabilizer (CYA). Enter your current free chlorine, your CYA, and your pool volume to get the exact amount of chlorine to add.
How much chlorine does my pool need?
Aim for a free chlorine level of roughly 7.5% of your cyanuric acid reading. At CYA 40 that is about 3 ppm; at CYA 80 (typical for salt pools) it is about 6 ppm. This is the single most misunderstood part of pool chemistry: “1-3 ppm” is only correct at low CYA, and following it in a heavily stabilized pool is how algae gets a foothold. Enter your numbers above and the calculator handles the conversion to an actual product amount.
How much liquid chlorine per 10,000 gallons?
One gallon of 12.5% liquid chlorine (sodium hypochlorite) raises 10,000 gallons by about 12.5 ppm, so a quart raises it roughly 3 ppm. Household bleach at 6% is about half as strong per gallon. The calculator scales this to your exact volume, target, and product strength instead of leaving you to do the arithmetic poolside.
Liquid chlorine, cal-hypo, dichlor or trichlor?
Liquid chlorine adds nothing but chlorine and salt, which makes it the routine workhorse. Cal-hypo is granular and strong but adds calcium every time. Dichlor and trichlor tablets add cyanuric acid with every dose, so they quietly raise your CYA — and therefore your chlorine target — all season. If your CYA keeps climbing, your tablets are the reason.
Ideal ranges
| Level | Target | Notes |
|---|---|---|
| CYA 0-20 (spa, unstabilized) | 1-3 ppm | Burns off fast in sunlight |
| CYA 30 | 2-4 ppm | Typical chlorine pool |
| CYA 40 | 3-5 ppm | |
| CYA 50 | 4-6 ppm | |
| CYA 70-80 (saltwater) | 5-7 ppm | Salt pools run higher CYA |
Frequently asked questions
How much chlorine do I add to a 10,000 gallon pool?
To raise free chlorine by 1 ppm in 10,000 gallons takes about 10 fl oz of 12.5% liquid chlorine, or roughly 2 oz by weight of 73% cal-hypo. Multiply by however many ppm you need. Enter your real volume above for the exact amount.
How long after adding chlorine can I swim?
After a routine dose, wait until the water has circulated for 15-30 minutes and free chlorine is back under about 5 ppm. After shocking, wait until it falls back to your normal target for your CYA.
Why does my chlorine disappear every day?
Either you have no stabilizer, so sunlight destroys it within hours, or something in the water is consuming it — usually early algae. Check CYA first, then look at whether chlorine holds overnight with the sun down.
Can I add chlorine and acid at the same time?
No. Never mix them or add them together — concentrated chlorine and acid produce toxic chlorine gas. Add one, let it circulate, then add the other.
Related calculators & guides
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