Marbled goby contrary to popular believe is not an air breather like the snakeheads. As such the water in the grow out pond needed to be oxygenated. Using small pump will always lead to malfuction due to something stuck in the pump. Using air stone and air pump will not get the water to move. Thus the solution is to use air lift. There are many design of air lift. We choose the simple air lift as the picture show. The movement of the air and water will kept the water material in the middle (vortex) where it is much easier to siphon off.
The float helps to keep the elbow above water.
The airlift in action.