Most swimming pool pumps come in one of four sizes: ¾ HP, 1 HP, 1.5 HP, and 2 HP. HP refers to the amount of horsepower a pump uses, and swimming pool pumps that use 2 HP provide the most amount of horsepower needed out of any other model. They are better suited for larger swimming pools or pools with more features.As mentioned, if you have a large or commercial swimming pool, or one with ample water features, choose a 1.5 or 2 HP swimming pool pump. The pool pump is the key piece of equipment in your system for quality water, so choosing the right size with the correct horsepower is essential. Calculate the amount of horsepower your pool pump needs to circulate the water below.