Cheap KOI Pond aeration needed.?

We have a pond that is 80 wide by 8 deep at the most. We've inherited about 3 dozen KOI fish and I want to aerate the pond. I'm interested in a low cost pumping sytem to perform the task and looking for ideas to perhaps just have a hose at the bottom emitting fresh air, without the high energy consumption of a submersible pump. My electricity costs are high enough, and I don't want to spend hundreds on solar or windmill systems. Besides, it only needs to run during the hottest months. Suggestions puh-leezz?