Coralife Aquarium Chillers - 1/10 HP, 1/4 HP, 1/2 HP and 1 HP offered. Determine the size you need and select. It's always best to get the next size up than what you are thinking. This gives the chiller less run time to cool your aquarium, which ultimately saves electricity and the life of the chiller components. Can also be used to cool water for Hydroponics.