If 15,000 gallons of water is the amount of water in your pool then ever 12 hours there should be a complete change (turnover) of 15,000 gallons of water by your pool pump. Unfortunately this may not be the way pumps really see it.
Similar to miles per gallon (MPG) your automobile gas mileage is quoted as and what your care actually gets are two different things so the gallons per minute (GPM) that your pool should have is not what the pump really does. So to minimize the consumption of energy and maximize the “turnover” we have a plan for a green way of accomplishing this.
Most pool owners will purchase a swimming pool pump not on how simple it is to operate or how efficient it is. They make their purchase on the total power or horsepower of the pump. Many sellers are offering a larger pump as a free upgrade to beat out a competitors offer. For this reason, the normal person ends up purchasing an exceedingly oversized pump.
1, 1.5, even 2 HP pool pumps are extremely common and for the average pool that is way too big. Most pool pumps are not designed to work efficiently but are made to have a multitude of features and be attractive.
California has enacted a law just recently putting a limit on your swimming pool pump, because of the how much of an issue oversized pool pumps have become.
If you are in the market to replace your pump you may want to consider the following. It is better to just look and purchase the right size of pump needed for your pool, because you could run a proper sized pump for 24 hours, as opposed to 12 hours of operation with an oversized pump. You not only will you save money, but since they run quieter they also will reduce noise pollution.