Pool Salt Calculator

A chlorine generator only works inside a narrow band of salinity, so the question is always how many bags to tip in. Enter the pool volume in gallons, the salinity your test reads now and the level the generator wants, and this returns pounds of salt, whole bags at the size you buy, and where the reading should land afterwards. It uses 8.34 pounds per gallon for water and assumes bagged pool salt at 99.8 percent sodium chloride, which you can change if you are using a lower grade. Nothing removes salt from a pool, so a second mode handles the other case and works out how much water to drain and refill to bring a high reading down. Test again a few hours after the pump has moved the water before trusting the new number.

Calculator Type
Measurements In
The metric setting reads the pool volume in litres and the hose in litres a minute, and gives the salt in kilograms. Salinity in ppm and the purity percentage are ratios, so they are the same number either way. The bag size list is separate and carries both, because a bag is a product rather than a unit.
Bag Size
Pound bags and kilogram bags are different products, not the same bag in two units, so both are listed and the measurement choice above does not change them. Pick the one you can actually buy.

Current salinity from a test strip or meter, and the level your chlorine generator asks for.

In US gallons, or in litres if the measurement choice is metric. Water volume, not the size of the shell. 100 to 1,000,000 gallons, or 378.54 to 3,785,411.78 litres.
Enter 0 for a pool that has never been salted. Parts per million by mass, which is the same figure in every country.
Most generators want 3,000 to 3,400 ppm. Follow the manual, not this box.
Bagged pool salt is normally 99.8 percent sodium chloride. Lower grades need more product.
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Measurements In
The metric setting reads the pool volume in litres and the hose in litres a minute, and gives the salt in kilograms. Salinity in ppm and the purity percentage are ratios, so they are the same number either way. The bag size list is separate and carries both, because a bag is a product rather than a unit.

Nothing takes salt out of a pool. You drain part of it and refill, and this is how much.

In US gallons, or in litres if the measurement choice is metric. Water volume, not the size of the shell. 100 to 1,000,000 gallons, or 378.54 to 3,785,411.78 litres.
Mains water is usually close to zero. Well water may not be.
In gallons a minute, or in litres a minute if the measurement choice is metric. 1 to 500 gallons a minute, or 3.79 to 1,892.71 litres a minute. Blank means 10 gallons a minute, or 40 litres a minute.
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