There is a grain aeration system for a grain bin. The system includes a gas entry duct configured to receive gas and a gas distribution pipe extending upwardly from the gas entry duct and having a height. The gas entry duct extends along a base of the grain bin. The gas distribution pipe includes a permeable section and an impermeable section. The permeable section includes a plurality of perforations. The permeable section is above the impermeable section. There is also a grain bin, having a surrounding wall and roof. There is a gas entry duct extending from outside the surrounding wall to inside the surrounding wall and a gas distribution pipe extending upward from the gas entry duct. The gas distribution pipe has a permeable section above an impermeable section.