An alternate system uses a fog or good mist injected in to the intake air stream. Although 
several commercial systems are available, 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 controlled by a two- stage thermostat enables more water to be applied on excessively warm, bright days. Temperature settings ought to be 5-10°F apart.
Algae growth in the pads may 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 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.
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 drinking water. A flow rate 113 gallon per minute per linear foot of pad system should be provided to assure adequate wetting.
In the most typical coolant system (fan and pad), the fans draw air through wet pads that prolong the length of one endwall or Greenhouse Auto Vent sidewall. Aspen and covered cellulose are normal pad materials that usually have life of 1 to 3 years. Approximately one sq . foot of pad are is needed for 20 square foot of floor area.