An alternate system runs on the fog or good mist injected in to 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 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 growth in the pads can become a problem that may decrease the effectiveness of the machine and result in accelerated deterioration of the pads. The addition of an Greenhouse Auto Vent algaecide to the water supply will help in control.
It is desirable, especially in hard drinking water areas, to add a wetting agent to the drinking water to obtain more uniform wetting of the pads. A commercial materials or liquid household detergent at the rate of 2 tablespoons per 100 gallons may be used.
Drinking water for the pads should be clean and lower in mineral content to prevent clogging and coating of the pads. A pump, pipes and gutters are accustomed to recirculate the drinking water. A flow rate 113 gallon per minute per linear foot of pad program 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 extend the length of 1 endwall or sidewall. Aspen and covered cellulose are normal pad materials that always have life of 1 to three years. Approximately one square foot of pad are is necessary for 20 square feet of floor area.