Bruce and Ted --
Oops. Hit the post button too soon!
Many thanks for your advice -- it is greatly appreciated. I think one of my goals for next summer was simply to cut the electric use and hence lower the monthly electric bill during the AC season. But the aerator really doesn't cost that much to run 24/7 -- and trying to run it part time looks like it could turn out to be a case of "penny wise, pound foolish."
I don't know too much about the mechanics of aeration. The unit I have is (I believe) a 1/3 hp unit that moves 1.5 cubic feet of air per minute, and pulls 3.1 amps. I have it located in a slightly offset position in the pond -- not at the deepest point but in about 6 feet of water (deepest is about 8' or so), in what looks like it might be the old spring stream channel. Believe me, it was a totally random "drop" back in September 2002! Probably influenced more by biting insects than by pond knowledge.
That idea of a second diffuser is pretty intriguing. Since most of the trout head up to a small area where the spring meets the pond and spend much of the summer there (most of July and almost all of August), that might be an ideal location for the second diffuser. That area seem to be the cold water "plume" -- a habitat usually no more than about 25 feet out into the pond; about three feet wide and 1.5' deep where it enters and widening to about 12 feet and maybe 3 feet deep -- that seems to be their "refuge." I know that my spring water emerges very low in DO and very high in nitrogen, so that sounds like the place for a secondary diffuser. (Note -- tried a little home aquarium type aerator up there two summers ago ... it didn't last but a week in the rigors of the outdoors.)
In the meantime, I know I'm going to be busy this winter "rebuilding" the aerator, hauling out the air stones and cleaning them, etc.
One comment about our climate: I grew up in southwestern Ohio, so I would say this climate is generally milder. We get some sub-zero weather in winter, but those days are far less common than days in the 50's. Then in the summer, we can get some 95+ days, but it almost always cools off well at night. I think that's the big difference a mountain climate offers. While my place isn't too high in elevation, it gets the benefits of the surrounding regional mountain climate. Night-time temps here often dip into the upper 50's -- that may be a big difference for trout survival, too.
My thanks again for your excellent advice. I'm not going to rush into anything (after all, it took me two years to decide to stop winter aeration!). I'm going to proceed slowly, ask a lot of questions and see what my aging back and thinning wallet can accomplish. -- Mike
