An alternate system runs on the fog or great mist injected in to the intake air stream. Although several commercial systems can be found, growers can assemble and set up their own system utilizing a high pressure piston pump and fog nozzles. The essential components are shown in Fig. 1. A two-stage system controlled 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 that will decrease the effectiveness of the system 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 water to obtain more uniform wetting of the pads. A commercial material or liquid household detergent at the rate of 2 tablespoons per 100 gallons can be used.
Water for the pads should be clean and lower 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 each and every minute per linear foot of pad system should be provided to make sure adequate wetting.
In the most typical cooling system (fan and pad), the fans draw air through wet pads that prolong the length of one endwall or sidewall. Aspen and coated cellulose are common pad materials that usually have life of 1 to 3 years. Approximately one square foot of pad are is needed for 20 square feet of floor area.
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