How Much Chlorine

How Much Salt to Add to a Pool (Pounds by Gallons and ppm)

By Tam Vu · Updated

On this page
  1. The formula
  2. Pounds of salt to raise the level by 500 ppm
  3. Before you add salt
  4. Safety and the label
  5. Salt and chlorine
  6. Sources

A salt-water pool makes its own chlorine from salt dissolved in the water. The salt cell only works within the range its maker sets, so the target comes from your cell's manual, not from a general chart. Once you know the target, the amount of salt is simple arithmetic.

Pool salt

The 2,800 and 3,200 ppm defaults are only example numbers. Use your own test result and your cell maker's target. If the target is below your current reading, the calculator tells you how much water to replace instead.

The formula

1 ppm is 1 milligram per liter, so:

pounds of salt = gallons × 3.785 × ppm to add ÷ 1,000 ÷ 453.6

That works out to about 8.35 lb of salt per 1,000 ppm in 1,000 gallons, or 0.835 lb per 100 ppm per 1,000 gallons.

Example: a 15,000-gallon pool reads 2,800 ppm and the cell's manual asks for 3,200 ppm. Add 400 ppm: 15,000 × 3.785 × 400 ÷ 1,000 ÷ 453.6 = 50.1 lb of salt.

Pounds of salt to raise the level by 500 ppm

Pool size Salt for +500 ppm
10,000 gallons 41.7 lb
15,000 gallons 62.6 lb
20,000 gallons 83.5 lb
30,000 gallons 125.2 lb

For a different rise, scale in proportion: +1,000 ppm takes twice these amounts.

Before you add salt

  • Know your gallons. A wrong volume makes every number above wrong. Use the pool volume calculator.
  • Use your cell's target. Salt cells are made by different companies and each manual sets its own range.
  • Too much is hard to undo. Chemicals can't take salt out of the water. The only fix is replacing part of the water, so add in steps and test again.

Safety and the label

The salt calculator works from the strength you select; the instructions on your salt bag and in your cell's manual are the final word. Virginia's Department of Health says to read the manufacturer's label, add chemicals to water and not water to chemicals, never add pool chemicals while the pool is in use, and wear the protective gear the label lists (VDH).

Salt and chlorine

A salt cell turns salt into chlorine, so the chlorine levels on the chemistry chart still apply. The CDC recommends at least 1 ppm free chlorine in pools, or 2 ppm if the pool uses cyanuric acid (CDC).

Sources