An alternate system uses a fog or fine mist injected in to the intake air stream. Although many commercial systems are available, growers can assemble and set up their own system utilizing a high pressure piston pump and fog nozzles. The essential components are demonstrated in Fig. 1. A two-stage system managed by a two- stage thermostat enables more water to be employed on excessively warm, shiny days. Temperature settings should be 5-10°F apart.
Algae growth in the pads can become a problem which will decrease the effectiveness of the machine 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 drinking water to obtain more uniform wetting of the pads. A commercial materials or liquid home detergent at the price of 2 tablespoons per 100 gallons may be used.
Drinking water for the pads ought to 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 water. A flow rate 113 gallon each and every minute per linear foot of pad program ought to be provided to guarantee adequate wetting.
In the most typical coolant system (fan and pad), the fans draw air through wet pads that expand the length of 1 endwall or sidewall. Aspen and coated cellulose are common pad materials that always have life of one to 
3 years. Approximately one sq . foot of pad are is needed for 20 square ft of floor area.
Greenhouse Auto Vent details and myths.