An alternate system runs on the fog or great mist injected in to the intake air stream. Although a number of commercial systems can be found, growers can assemble and install their own system using a ruthless piston pump and fog nozzles. The essential components are demonstrated in Fig. 1. A two-stage system controlled by a two- stage thermostat allows more water to be applied on excessively warm, bright days. Temperature settings should be 5-10°F apart.

Algae development in the pads may become a problem which will reduce the effectiveness of the machine and lead to accelerated deterioration of the pads. The addition of an algaecide to the drinking water supply can help in control.

It really is desirable, especially in hard drinking water areas, to add a wetting agent to the drinking water to obtain additional uniform wetting of the pads. A commercial materials or liquid household detergent at the rate of 2 tablespoons per 100 gallons may be used.

Water for the pads ought to be clean and lower in mineral content to avoid clogging and coating of the pads. A pump, pipes and gutters are accustomed to recirculate the drinking water. A flow rate 113 gallon each and every minute per linear foot of pad system ought to be provided to guarantee adequate wetting.

In the most common cooling system (fan and pad), the fans draw air through wet pads that lengthen the length of one endwall or sidewall. Aspen and covered Greenhouse Auto Vent cellulose are normal pad materials that always have life of one to three years. Approximately one square foot of pad are is necessary for 20 square feet of floor area.