How Much Chlorine You Need To Put In a Swimming Pool?

how much chlorine in swimming pool

There are a lot of factors that into how much chlorine our swimming pools need, but with a little common sense and reading the directions it isn’t all that complicated. The biggest factor in applying chlorine to pool water is knowing how many gallons of water there are in your pool. To measure the volume of water in your pool, so we need a little formula to help us out, so if you lost your pool specifications don’t panic.

Volume of a Rectangular Pool in Gallons

To find the volume of a rectangular pool you need to know the width and the length and the depth.

(Length x Width) x Depth = Cubic Feet

Now all we have to do is change the cubic feet into gallons. It isn’t hard, and it is just another simple formula. In one cubic foot there are 7.48 gallons, so the answer is simple. Just plug in the numbers.

Cubic Feet x 7.48 = Gallons

Volume of a Round Pool in Gallons

The formula for a round pool is a little more complicated, if you just plug in the numbers it is a breeze. We have to look at our round swimming pool as a cylinder, so the volume in cubic feet is as follows. Now don’t panic about the radius because all it is a point from the center of the pool to the edge.

(3.14)(radius^2)(height) = Cubic Feet

Now we just need to change the cubic feet result into gallons and we are set.

Cubic Feet x 7.48 = Gallons

Do you see how simple it is? Now how much chlorine to add to your swimming pool? You need to know how many ppm of chlorine is already in your pool. It is easiest to get a chlorine testing kit at your pool supply store. Optimum levels of chlorine for your pool are 1 ppm to 3 ppm, and ppm is parts per million. If you have a lot or rain you may want to keep it above 1 part per million, and also if you have a lot of high temperature days. If your chlorine levels out to 1 part per million you want to add 0.00013 ounces per gallon to raise it up to where you are satisfied.


4,000 Gallons x 0.00013 = 0.52 ounces of chlorine

9,000 Gallons x 0.00013 = 1.17 ounces of chlorine