This is the ideal cooling solution for small aquariums. This quiet, reliable efficient chiller uses advanced thermoelectric technology to directly convert electricity into cooling power. Can be easily bulkheaded through a 1 1/4". hole into siphon overflows, prefilters, sumps or even directly into plastic aquariums. Provides continuous chilling when plugged in to a power source, it does not have an on/off switch. A separate temperature controller must be used to turn the device on or off at pre-determined temperatures. A single IPAC-50W chiller can cool 10 gallons of water 6F to 8F, 20 gallons of water 3F to 4F and 40 gallons of water 1F to 2F below ambient air temperature in a standard aquarium. For greater cooling multiple units can be used.