Water Cooled Grow Light Fixtures are often more efficient to run than their air cooled equivalents. Another added benefit of water cooled reflectors and hoods is that the water cooling leaves the glass cool so that you can get the reflector closer to your plants without burning them. Water cooled lights also reduce the requirements of an air conditioning unit. To conserve water the units are generally cooled using a reservoir and water pump. Depending on the size of the reservoir you may require a water chiller.