Water cooled lighting works the same way as other high power hydroponic lighting, with the exception that the replacable lamp is encased within two tubes. Water flows between the tubes and there is an air gap between the lamp and the inner tube designed for maximum thermal transfer. This allows the light to run with the casing being cold to the touch, and ideal for close proximity to plants. This allows plants to grow much closer to the light, allowing plants to collect more light without burning. In addition, this arrangement allows some grace, should there be a problem with water pumping.

The cold water is taken from a reservior (not shown, not included). Our demonstration system uses a green, plastic water barrel for a reservior. These are available from any good garden centre. Any source of cold water is suitable, although a clean source of water will reduce maintainance. A large reservior is prefered because this is suitable for disappating more heat. Suitably large reserviors can be shared by multiple water cooled lights, although it may be preferable to isolate water supplies, to prevent the potential spread of algae and reduce potential problems due to lack of coolant. (We have heard of people using hydroponic nutrient reserviors for cooling, although this practice is not recommended at all.)

Overall, utilising water cooled lighting is quite easy and is not restricted to experts. Finally, please note that water cooled lighting is only available for 400W and 600W High Pressure Sodium [HPS] lamps and Metal Halide [MH] lamps.