An alternate system runs on the fog or fine mist injected into the intake air stream. Although many commercial systems can be 
found, 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 enables more water to be employed on excessively warm, bright days. Temperature settings Greenhouse Exhaust Fan should be 5-10°F apart.
Algae development in the pads can become a problem that may decrease the effectiveness of the system and result in accelerated deterioration of the pads. The addition of an algaecide to the drinking water supply can help in control.
It is desirable, especially in hard drinking water areas, to add a wetting agent to the drinking water to obtain additional uniform wetting of the pads. A commercial materials or liquid household detergent at the rate of 2 tablespoons per 100 gallons can be used.
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 accustomed to recirculate the water. A flow rate 113 gallon per minute per linear foot of pad program should 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 normal pad materials that always have life of one to three years. Approximately one sq . foot of pad are is needed for 20 square ft of floor area.