Ryan,
Again thanks for the suggestions. I really like the suggestion on changing the vent pipe elbow and will consider this. As for the check value do they make them for 4" pipe? Figure that I will have to make an adaptor that screws on to the top of the vent and reduces the pipe size down to 1 1/2". Then my shop vac would fit over it and I can get a check value for that size of pipe. Not sure how many times I will manually siphon the pond down, just nice to konw this can be done.
