Both of these diffusers floated about 50 cm above the bottom of the dugout. They were held in place with weights attached to the diffuser by rope every 1.2 m. It consisted of a cylindrical rubber tube 28 cm long and 7.5 cm in diameter with rows of slits 2 mm long spaced approximately 2.0 - 2.5 mm apart. Comparison of energy expenditure and amount of aeration of study dugouts. Treatments are described in Table 1.
Air flow is given in litres per minute.
The location of the aeration device in the dugout varied somewhat. The open-ended tubes were located near the water intakes which in both cases were located away from the centre of the dugout. Two surface aerators were also tested. Both of these consisted of a small electric motor oriented vertically in the dugout and supported by a float. A small propeller was attached to the shaft of the motor and which forced a plume of water into the air.