An alternate system uses a 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 shown in Fig. 1. A two-stage system controlled by a two- stage thermostat allows more water to be employed on excessively warm, bright days. Temperature settings ought to be 5-10°F apart.

Algae growth in the pads can become a problem that may decrease the effectiveness of the system and lead to 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 Greenhouse Auto Vent wetting agent to the drinking water to obtain additional uniform wetting of the pads. A commercial material or liquid home 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 drinking water. A flow rate 113 gallon each and every minute per linear foot of pad program ought to be provided to make sure adequate wetting.

In the most common coolant system (fan and pad), the fans draw air through wet pads that lengthen the length of one endwall or sidewall. Aspen and coated cellulose are normal pad materials that usually have life of 1 to 3 years. Approximately one square foot of pad are is necessary for 20 square feet of floor area.