Cary -- good idea!! Let's start calling them de-icing systems! That should cut down on a lot of the confusion on what we are doing and why!
Others intersted in this string: I interacted with Lew this morning via e-mail. Let me put a summary here. SDSU is located almost straight west of Lew, so we probably have similar winters (his may be a little milder just south of the Twin Cities). The true gravel pits around here (those dug down into the ground water) do not need aerators as long as they have 10-12 feet of water. Apparently, there is enough ground water movement to keep the dissolved oxygen from hitting zero. That was a surprise for me to learn, as "everyone" says that ground water has no oxygen. However, the shallow aquifers must have some.
In contrast, the hill ponds (dams built across draws) around here have to be VERY deep to avoid winterkill. During that last bad winter (2000-2001, I think) we had winterkill on two ponds that had aerators and were quite deep (one is over 20 ft). These ponds were 3 and 7 acres, so it's not like they were tiny. Winters are tough here. However, this is when I first learned about the potential for "super-cooling" of water over a long, hard winter. Several of us from the Pond Boss Forum monitored dissolved oxygen and temperature this winter, and found little evidence of super-cooling. However, it was a very mild winter (ice was not especially thick, and little snow cover on the ice). So, it probably was not a good test year.
Anyway, here was my thought for Lew. If he had time (that is, could wait a year), I wondered if he should monitor dissolved oxygen next winter and see if he really has a problem?? Just a thought.
