An alternate system uses a fog or good mist injected in to 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 demonstrated in Fig. 1. A two-stage system managed by a two- stage thermostat enables more water to be applied 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 system and result in accelerated deterioration of the pads. The addition of an algaecide to the water supply can help 
in control.
It really is desirable, especially in hard water areas, to add a wetting agent to the water to obtain more uniform wetting of the pads. A commercial material or liquid home detergent at the price of 2 tablespoons per 100 gallons may 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 accustomed to recirculate the drinking water. A flow rate 113 gallon each and every minute per Greenhouse Auto Vent linear foot of pad system should be provided to make sure adequate wetting.
In the most common cooling system (fan and pad), the fans draw air through wet pads that lengthen the length of one endwall or sidewall. Aspen and covered cellulose are normal pad materials that always have life of 1 to three years. Approximately one square foot of pad are is needed for 20 square foot of floor area.