Micheal, the well water running through the pipe should be 55 degrees or less, this would act like an air conditioning coil if it was submerged in your pond cooling the surrounding water before it actually entered into your pond elsewhere, thus creating a temperature sweet spot next to the pipe. With the horizontal aeration technique ewest mentioned you would aerate the incoming water by having the the jets pointed horizontally along the surface to disturb the surface as it mixed with the existing pond water. Bruce can explain his horizonatal aeration technique much better than I can as he has been experimenting with sweeper nozzles and his well water to aerate his ponds with great success. Basically it's the motion of the incoming water distrubing the surface water of your pond that faciltates a high oxygen transfer rate into the water. The more water that is disturbed by the motion and exposed to the air, the higher rate of transfer there is.
In northern climates this could also be used in reverse in creating warm pockets in the winter time which might improve growth rates on species like yellow perch if you could create warm pockets that were 5-10 degrees above your winter time norms in the deeper areas of your pond. Basically you would be using the submereged pipe to thermally transfer the well water temp before the water actually makes into your pond. Just so you know, this is just an idea based on the "strange pond" thread I saw earlier this summer. South central NE is not a place where trout could actually survive very well in the summer without some help, daytime highs are in the 90's and 100's with lows at night in the mid 80's.
