You may want to look into a Venturi valve. It picks up air as water passes and gets infused with the outflow. Lots of info available on how they work and even how to DIY one.

.10 surface acre pond, 10.5 foot deep. SW LA. The epitome of a mutt pond. BG, LMB, GSF, RES, BH, Warmouth, Longear Sunfish, Gambusia,Mud Minnows, Crappie, and now shiners!!...I subscribe!!