The aeration bench ventilation is what supports the potting mix and plants above the water tank. air gap necessary for the lower bench of aeration and water. Cracks and holes are too full to ensure the potting mix can not flow freely, and never be too saturated with water. practical standpoint, only water as it enters the surface of potting mix after planting, rainwater. Design allows currently about 1 / 2 all the rainwater to accumulate in the water tank before concluding with an additional overflow.
