An alternate system uses a fog or good mist injected into the intake air stream. Although many commercial systems can be found, growers can assemble and install their own system utilizing a high pressure piston pump and fog nozzles. The essential components are shown in Fig. 1. A two-stage system managed by a two- stage thermostat enables more water to be applied on excessively warm, bright days. Temperature settings should be 5-10°F apart.
Algae development in the pads can become a problem that may decrease the effectiveness of the system and result in accelerated deterioration of the pads. The addition of an algaecide to the water supply will help in control.
It really is desirable, especially in hard 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 price of 2 tablespoons per 100 gallons may be used.
Water for the pads should be clean and low in mineral content to prevent 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 system ought to be provided to make sure adequate wetting.
In the most common cooling system (fan and pad), the fans draw air through wet pads that extend the length of 1 endwall or sidewall. Aspen and coated Greenhouse Auto Vent cellulose are normal pad materials that always have life of 1 to 3 years. Approximately one square foot of pad are is necessary for 20 square feet of floor area.