Commercial Clearwater Company, Inc.
How much chemical to use The first step in determining how much chemical to use is to test the pool or spa water and determine if, and how much, of a change is necessary. How much chemical is needed to increase or lower a parameter is based on a simple mathematical formula that accounts for the total water volume of the pool, the chemical to be used, and the amount of that chemical required to raise the parameter by 1 to 10 ppm.
The Formula: HMC (How Much Chemical) = A x B x C A is the amount of chemical called for on the label or manufacturer's instructions B is the ratio between the actual pool gallons compared to the number of gallons listed the chemical label or manufacturer's instructions. B1 = Actual pool gallons; B2 = Gallons on Label or instructions
B = B1÷B2C is the ratio between the desired chemical change and the change indicated on the chemical label or manufacturer's instructions.
C1= desired change (target reading - actual reading); C2 = Change indicated on label or instructions
C = C1÷C2