An alternate system uses a fog or great mist injected in to the intake air stream. Although a number of commercial systems can be found, growers can assemble and set up their own system using a ruthless piston pump and fog nozzles. The essential components are demonstrated in Fig. 1. A two-stage system controlled by a two- stage thermostat allows more water to be employed on excessively warm, bright days. Temperature settings should be 5-10°F apart.
Algae growth 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 drinking water supply will help in control.
It really 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 household detergent at the rate of 2 Greenhouse Auto Vent 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 drinking water. A flow rate 113 gallon per minute per linear foot of pad program ought to be provided to make sure adequate wetting.
In the 
most typical cooling system (fan and pad), the fans draw air through wet pads that prolong the length of one endwall or sidewall. Aspen and covered cellulose are normal pad materials that always have life of one to 3 years. Approximately one sq . foot of pad are is needed for 20 square ft of floor area.