An alternate system runs on the fog or great mist injected into the intake air stream. Although a number of commercial systems can be found, growers can assemble and set up their own system using a high pressure 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 ought to be 5-10°F apart.
Algae growth in the pads may become a problem that may decrease the effectiveness of the machine and lead to accelerated deterioration of the pads. The addition of an Greenhouse Auto Vent algaecide to the water supply can help in control.
It really is desirable, especially in hard water areas, to include a wetting agent to the water to obtain more uniform wetting of the pads. A commercial materials or liquid home detergent at the rate of 2 tablespoons per 100 gallons can be used.
Drinking water for the pads should be clean and lower in mineral content to avoid clogging and coating of the pads. A pump, pipes and gutters are accustomed to recirculate the water. A flow rate 113 gallon each and every minute per linear foot of pad system should be provided to assure 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 normal pad materials that usually have life of one to three years. Approximately one square foot of pad are is necessary for 20 square feet of floor area.