An alternate system uses a fog or fine mist injected in to the intake air stream. Although several commercial systems are available, growers can assemble and install 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 development in the pads may 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 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 more Greenhouse Auto Vent uniform wetting of the pads. A commercial material or liquid home detergent at the price of 2 tablespoons per 100 gallons can be used.
Drinking water for the pads ought to 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 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 typical coolant system (fan and pad), the fans 
draw air through wet pads that lengthen the length of 1 endwall or sidewall. Aspen and covered cellulose are common pad materials that always have life of one to 3 years. Approximately one sq . foot of pad are is necessary for 20 square foot of floor area.