An alternate system runs on the fog or good mist injected in to the intake air stream. Although several commercial systems can be found, growers can assemble and install their own system utilizing 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 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 can become a problem which will reduce the effectiveness of the Greenhouse Auto Vent machine and lead to 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 drinking 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 can be used.
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 used to recirculate the water. A flow rate 113 gallon per minute per linear foot of pad program ought to be provided to ensure adequate wetting.
In the most typical coolant system (fan and pad), the fans draw air through wet pads that 
expand the length of one endwall or sidewall. Aspen and covered cellulose are common pad materials that usually have life of 1 to three years. Approximately one sq . foot of pad are is needed for 20 square ft of floor area.