But, if his pump clogs with those bugs wouldn't a pre-filter do the same thing, Colleen? That's why I don't have a pre-filter. If it clogs, then my pump is done until the ice is gone. I don't have a pre-filter on any of my pumps, except the filter on the skimmers is a sort of pre-filter. I think that was a good idea for the skimmer that feeds the bog; however, THAT bog seems to have clogged lines. Going to hook up the 4200 pump to those lines come spring and see if I can "blow it out". Running very slow last fall, so shut it down. The 4200 that is on a crate in the goldfish pond and runs that bog, no prefilter except the "cage" on the pump, and it's running perfectly. Never have to hardly even clean off the cage. You definitely have a good situation going there, Colleen. Wondering if those of us with ponds more out in the open, no fences, houses, etc. sheltering it from extra wind and cold, would have as much luck with your system. I am going to try to do a slower water flow closer to the surface next year, though, in both ponds. Somehow I will try to turn the pumps sideways and have them closer to the surface to push water there to keep ice at bay, and add more circulation. I guess if I aim them at where the heater will be if/when plugged it in, that will help as well. I sure don't want any of those water bugs. I read that they are in "fishless" water, so the fish must eat them usually.