An alternate system uses a fog or good mist injected into the intake air stream. Although a number of commercial systems are available, growers can assemble and set up their own system utilizing 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 allows more water to be employed on excessively warm, shiny days. Temperature settings ought to be 5-10°F apart.
Algae development in the pads can become a problem which will decrease the effectiveness of the system and lead to accelerated deterioration of the pads. The addition of an algaecide to the drinking water supply will help in control.
It is desirable, especially in hard drinking water areas, to include a wetting agent to the water to obtain additional uniform wetting of the pads. A commercial materials or liquid household detergent at the price of 2 tablespoons per 100 gallons can be used.
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 used to recirculate the water. A flow rate 113 gallon each and every minute per linear foot of pad Greenhouse Exhaust Fan program should be provided to guarantee 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.