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 install their own system using a ruthless piston pump and fog nozzles. The essential components are shown in Fig. 1. A two-stage system managed by a two- stage thermostat enables more water to be applied on excessively warm, bright days. Temperature settings Greenhouse Exhaust Fan should be 5-10°F apart.
Algae growth in the pads can become a problem that 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 really is desirable, especially in hard water areas, to include a wetting agent to the water to obtain additional uniform wetting of the pads. A commercial materials or liquid home detergent at the price of 2 tablespoons per 100 gallons can be used.
Water for the pads should 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 per minute per linear foot of pad program should 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 1 endwall or sidewall. Aspen and covered cellulose are normal pad materials that always have life of one to 3 years. Approximately one square foot of pad are is necessary for 20 square foot of floor area.