1/5-compact 1/2 drop-in style will work from 50 gallons to 450 gallons. It is easy to install, has an extremely flexible hose that can be lengthened to 10 ft. It will maintain temperatures from 80 degrees to 50 degrees depending on tank size and volume of water. All chillers come with an easy to program electronic controller. The high performance Copeland Condensing unit insures the long life of this unit.