How to Lower Salt Levels in a Pool

Calculating How Much Water to Drain

Test your pool’s salinity with a test strip. Pool test strips will quickly tell you how much salt is in your pool (which will help you figure out how much water you need to drain). Scoop about 1 in (2.5 cm) of pool water into a cup, then take a test strip and put it into the water. Wait about 5 minutes, then look at the reading on the strip and compare it to the numbers on the bottle. The reading on the strip will give you a number between 1 and 10. These numbers correlate with the numbers on the bottle of test strips that will tell you how much salt is in your pool. The recommended range is between 2,700 and 3,400 parts per million (PPM). The optimal salinity for a pool is 3,200 PPM. Lowering the salt levels in your pool can sound like a pain, but it’s important to keep them balanced. Too much salt can corrode your pool equipment, and since salt doesn’t evaporate, your salt levels won’t get lower on their own. However, swimming in a pool that’s too salty isn’t dangerous for you or your family.

Find your pool’s overall volume. If you’ve filled your pool to capacity, check the unit’s user manual to find out the maximum amount of water it can hold. If your pool is not completely full, or if you can’t find its maximum volume anywhere, you can calculate how much water it contains using the following formulas: For rectangular pools: width x length x depth x 7.48 US gal (28.3 l). For circular pools: π x radius² x depth x 7.48 US gal (28.3 l). For oval pools: π x ½ width x ½ length x depth x 7.48 US gal (28.3 l). For variable depth pools, find the unit’s average depth using the formula shallow end depth x deep end depth ÷ 2. When doing your calculations, use this number in place of depth. For irregularly shaped pools, use the previous formulas to find the measurements of each individual section, then add them together to calculate the pool’s volume.

Calculate how much water you need to drain using PPM and volume. First, subtract your recommended salt PPM from your current salt PPM. Then, divide that number by the current salt PPM. Finally, multiply that number by the pool’s total volume to tell you how much water you need to drain. For example, if your salt level is 4,500 PPM and ideally it should be 3,200 PPM, you would calculate 4500 - 3200 = 1300. Take that number and divide it by your current salt PPM to get 1300/4500 = 0.2888. Finally, multiply that number by the number of gallons in your pool: 10,000 x 0.29 = 2,900 gallons of water to remove.

Draining and Refilling the Pool

Purchase or rent a pool drainage pump. You can rent a pump for between $25 and $40 an hour or purchase a pump for anywhere between $100 and $1000, depending on the quality. Pumps are available from most pool supply and home improvement stores and typically come in 1 of the following forms: Submersible pumps, which sit completely inside the water and are usually more affordable than above-ground pumps. Above-ground pumps, which sit next to a pool and are usually faster and more powerful than submersible pumps.

Hook your pump up to the pool. If you’re using a submersible pump, place the pump inside the pool completely underwater. If you’re using an above-ground pump, connect it to the pipes on the outside of your pool. Direct the pool water into your yard or your home’s sewer clean-out. In most cities, you cannot discharge pool water into a public area, so be sure to direct it back onto your property. Your sewer clean-out is a small, circular hole covered by a miniature manhole cover. Look for it in the area immediately surrounding your house. Not sure where to drain your water? Check your local county or city’s website.

Track the amount of water going out as you drain your pool. Most pumps drain at a rate of 12 gallons per minute, but you can check your owner’s manual to be sure. Track how much water you’ve drained by dividing your drain rate by the amount of water you need to drain. For instance, if you need to drain 2,900 gallons, you would divide 2,900 / 12 = 241 minutes or 4 hours.

Fill your pool with fresh water. Connect a rubber hose to an indoor or outdoor faucet and run it to your pool. Then, turn the faucet on and let the pool fill up with fresh, unsalted tap water equal to the amount of water you removed earlier.

Check your pool’s current salt level. After filling your pool with water, mix a small section of it with a pool brush or pole for 2 to 3 minutes. Then, test that area of the water to get a preliminary salt reading. If it is still above the pool’s recommended PPM, you may need to dilute the water further. If it is below the recommended PPM, you’ll need to add more salt to the pool.