Sorry for the delay. The pond is spring fed and the bottom temp is quite cool. There is no danger of the water becoming too warm. I elevated the difusser to the 18' mark and the pump is still running quite well.
Is it common to not see the rainbows at all? I really have not tried seriously to fish any out. Maybe three quarters of an hour with a few worms. I would assume that they are still there as other creatures such as water-bugs, frogs and tadpoles are not running rampant. Last spring and summer it was writhing with these creatures until I dumped the trout into the mix.
