Things You Will Need
Pool measurements, calculator
The first step is to know how many gallons of water are in your pool. The basic calculations for pool gallons of water are as follows: Rectangular and square pools are Length x Width x Average Depth x 7.5, Kidney, Oval or Round pools are Length x Width x Average Depth x 5.9. The average depth is calculated by adding the number of feet at the deep end and the shallow end and dividing by 2. An example is the deep end is 6 feet and the shallow end is 3 feet, then the average depth is (6+3)/2 = 4.5.
The next step is to determine the minimum flow rate that must be maintained to meet the recommended circulation times. This is calculated by taking the number of gallons figured in step one above and dividing by the desired turnover times divided by 60. An example is: 25,000 gallons of water in the pool, turnover every 8 hours. = 25,000 gallons /turnover every 8 hours/60 = 52 gallons per minute. (25,000/8/60=52)
The next step is to determine the maximum flow rate. The flow rate to any pool is limited by the piping and the other equipment attached to the system. Generally a 2.0 inch pipe can provide a maximum flow of 73 gallons per minute while a 1.5 inch pipe can only handle 42 gallons per minute. Make sure that the intake and return lines support the same level of flow.
Filters also have a maximum flow rate. If you exceed the flow rate, the filter could be damaged and not operate properly. The three main types of pool filters are cartridge filters, sand filters, and D.E. filters. The manufactures of each will provide the maximum and best flow rates of their filters. I recommend using the "best" flow rate as opposed to the maximum flow rate for better cleaning results.
Now that you know the range between the minimum and maximum flow rates, you can select the proper size pump for your pool. If you have a pool with no spa attached you can choose a pump on the lower end of the range. If you have a spa attached in addition to the pool you will need a pump on the higher end of the range to accommodate the spa jets.
Making sure that you have the correct size pump and motor for your swimming pool or spa is one of the most important steps to ensure a clean and safe swimming pool. Take the necessary steps that are involved in determining the proper size pump for your pool and enjoy a clean and safe for years to come.
Tips & Warnings
The filter needs to be cleaned and serviced on a regular basis. This is usually when the pressure gauge on the filter increases 8 to 10 psi (pounds per square inch) from a baseline reading taken when a new cartridge is installed or the other filter types are back flushed and clean.
The proper chemical treatment and chemical balance are also two important parts in making a safe and clean water environment.