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 install 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 allows more water to be employed on excessively warm, shiny days. Temperature settings ought to 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 addition of an algaecide to the water supply will help in control.

It Greenhouse Auto Vent really is desirable, especially in hard water areas, to add a wetting agent to the water to obtain additional uniform wetting of the pads. A commercial materials or liquid home detergent at the rate of 2 tablespoons per 100 gallons may 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 used to recirculate the drinking water. A flow rate 113 gallon per minute per linear foot of pad system ought to be provided to make certain adequate wetting.

In the most common cooling system (fan and pad), the fans draw air through wet pads that lengthen the length of one endwall or sidewall. Aspen and covered cellulose are normal pad materials that usually have life of one to three years. Approximately one sq . foot of pad are is necessary for 20 square feet of floor area.