Jeff, if you use PVC, drill some 2/16" holes in the very top of the pipe, and some near the bottom. That will allow the air inside the pipe out, and allow them to sink.
I would set traps on the bottom in 4'-8' of water. In the Spring, when the water is cooler, set them shallower, maybe 3'-6'. I would not set them where any part of the trap was below the thermocline if one sets up in your pond.
Perfect, thanks! Will do. Swimming in it last summer, it was very cold down deep (greater than 10'). So I'm assuming I have a thermocline. Looking at budget, I may not get aeration in this summer..
