An alternate system runs on the fog or fine 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 utilizing a high pressure 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 employed on excessively warm, shiny days. Temperature settings should be 5-10°F apart.
Algae development in the pads can become a problem which will reduce the effectiveness of the machine and lead to accelerated deterioration of the pads. The Greenhouse Exhaust Fan addition of an algaecide to the drinking water supply can help in control.
It really is desirable, especially in hard water areas, to include a wetting agent to the drinking 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 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 make sure adequate wetting.
In the most 
common coolant system (fan and pad), the fans draw air through wet pads that expand the length of one endwall or sidewall. Aspen and coated cellulose are common pad materials that always have life of one to 3 years. Approximately one sq . foot of pad are is needed for 20 square foot of floor area.