Increased aeration can transform a fishery by promoting extended feeding. During hot weather, dissolved oxygen levels may fall dramatically, resulting in fish becoming torpid. A feeding fish may have an oxygen requirement three times the level of a non-feeding fish. Aerators can maintain a more consistent level of dissolved oxygen which will also add long term health benefits for the fish stocks.
Paddle-wheel aerators resemble miniature versions of the paddle wheels normally associated with steamers on the Mississippi River. When operational, each partly-submerged wheel turns through a vertical plane, causing the water to become aerated as the blade chop into the water. Water raised by the paddle then falls back into the fishery with a much higher oxygen level. Paddle-wheel aerators can create a wake up to 50 meters behind them.
As a rule of thumb, paddle-wheel aerators are 50 per cent more efficient than either air-injection devices or air-diffusion methods. Surface agitators can be controlled with a time switch. As soon as they are switched on they work at 100 per cent efficiency. This is a major benefit as they can be used between dusk and dawn, the period of lowest oxygen concentrations, thereby preventing seasonal de-oxygenation problems.