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How Much Chlorine Should Be Used in a 1000 Gallon Pool?

By Contributor ; Updated September 21, 2017
Crystal clean pool water.

When it comes to sanitizing your pool water one of the best chemicals to use is chlorine. Because chlorine is a corrosive it must be dispensed into the pool water at the proper rate otherwise it could become harmful to anyone swimming in the water.

Types of Chlorine

There are basically three forms of chlorine that you may find in a pool. The first is free available chlorine or sometimes referred to as residual chlorine. This is the amount of chlorine in the water that will actually sanitize the water by killing bacteria and algae. The second form is combined chlorine which occurs when there is not enough free available chlorine in the water. This actually creates undesirable irritants in the water because it is not being properly sanitized. The third is total chlorine, which is a measure of free available chlorine and combined chlorine in the water. The form should always concern yourself with is free available chlorine as that is the one that works to keep your pool water clear and clean.

Adding Chlorine to Your Pool

Free available chlorine is available in granular and solid forms. Solid 1- or 3-inch tablets are slow dissolving while granular will rapidly dissolve in the water. When using granular chlorine it is best to first dissolve it into a bucket of water, and then add the water mixture to the pool water. Unless your pool is made of concrete, chlorine should never be added directly to the water. If it comes in direct contact with the walls or bottom it may damage materials such as fiberglass or plastic. A general rule you can follow when adding chlorine is 1/2 ounce for every 500 gallons of water on a weekly basis. If you have a 1,000 gallon pool an ounce a week should be enough to effectively sanitize the water.

Checking Chlorine Levels in the Water

Because there are many factors that affect the amount of free available chlorine in the water, you need to test the pool on a regular basis. Some of these factors include water temperature as the higher the temperature the more rapid the chlorine will disperse. Exposure to sunlight as well as heavy usage will also increase chlorine consumption. Using a test kit that you can find anywhere pool supplies are sold, you can measure the current amount of free available chlorine. An acceptable reading would be within 1-3 ppm (parts per million) with the ideal setting being 2 ppm. If the water reads lower than 1 ppm your will need to slowly add some additional chlorine to raise the level. If the reading is above 3 ppm, you should refrain from swimming in the water until the chlorine level drops below 3.


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