An alternate system uses a fog or good mist injected in to the intake air stream. Although many commercial systems can be found, growers can assemble and install their own system using a high pressure piston pump and fog nozzles. The basic 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, bright days. Temperature settings should be 5-10°F apart.
Algae growth in the pads may become a problem which will reduce the effectiveness of the machine and result in accelerated deterioration of the pads. The addition of an algaecide to the water supply will help in control.
It really is desirable, especially in hard drinking water areas, to include a wetting agent to the drinking water to obtain more uniform wetting of the pads. A commercial material or liquid household detergent at the rate of 2 tablespoons per 100 gallons can be used.
Drinking water for the pads ought to be clean and low in mineral content to avoid 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 ought to be provided to make sure adequate wetting.
In the most typical coolant system (fan and pad), the fans draw air through wet pads that extend the length of one endwall or sidewall. Aspen 
and coated 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.
We would certainly enjoy to aid you with anything you should understand about Greenhouse Auto Vent.