The Pool Drain Percent Calculator is used to determine the percent or fraction of water to be drained to reach a Target for a specific condition in the water.

The problem is this. A condition in the pool is too high and you need to drain some water. However, the make up or source water also has some level or concentration of that condition in it. How do you figure out how much to drain from the pool and end up with the desired Target?

Using the Pool Drain Percent Calculator, you enter the condition in the pool water, then enter the Target or Desired level in the water and finally, enter the level or concentration of the condition in the source or make up water.

Example #1

Pool has 600 ppm Calcium Hardness. Target for Calcium Hardness in the pool water is 350 ppm. Source or make up water has 150 ppm calcium hardness.

In cell Condition in Pool enter 600

In cell Target Condition enter 350

In cell Condition in Source enter 150

Read Drain 55% in Amount to Drain. This is the percentage of the average depth that should be drained and refilled with source water to achieve the Target of 350 ppm calcium hardness.

Example #2

Pool has 420 ppm CYA (cyanuric acid). Target for CYA in pool water is 50 ppm. Source or make up water has 0 (zero) CYA.

In cell Condition in Pool enter 420

In cell Target Condition enter 50

In cell Condition in Source enter 0

Read Drain 88% in Amount to Drain. This is the percentage of the average depth that should be drained and refilled with source water to achieve the Target of 50 ppm CYA.