HP refers to the amount of horsepower a pool pump uses, and 1 HP means that these swimming pool pumps use much less energy than others on the market. Keep in mind 1 HP pumps are not designed for large pools, which typically require 1.5 or 2 HP pool pumps.Pool Express offers a large inventory of 1 HP swimming pool pumps and even ¾ HP pool pumps. These models are perfect for most pool sizes and are a great way to cut back on energy use. The amount of HP the pool pump needs depends on the size and shape of your pool, and how it is used. Each model is from well-known brands in the swimming pool industry, including Pentair, Hayward, and the new energy efficient EcoPump.