An alternate system runs on the fog or fine mist injected into the intake air stream. Although many commercial systems are available, growers can assemble and set up their own system using a ruthless piston pump and fog nozzles. The basic components are proven in Fig. 1. A two-stage system managed by a two- stage thermostat enables more water to be applied on excessively warm, shiny days. Temperature settings should be 5-10°F apart.
Algae development in the pads can become a problem which will decrease the effectiveness of the machine and result in accelerated deterioration of the pads. The addition of an algaecide to the water supply can help in control.
It 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 Greenhouse Auto Vent materials or liquid household detergent at the rate of 2 tablespoons per 100 gallons can be used.
Drinking water for the pads should be clean and low in mineral content to avoid clogging and coating of the pads. A pump, pipes and gutters are used to recirculate the drinking water. A flow rate 113 gallon per minute per linear foot of pad program should be provided to make certain adequate wetting.
In the most common cooling system (fan and pad), the fans draw air through wet pads that extend the length of one endwall or sidewall. Aspen and covered cellulose are normal pad materials that usually have life of one to 3 years. Approximately one square foot of pad are is needed for 20 square ft of floor area.