In article ,
Michael Shaffer wrote:

Do check valves effect flow at all?


Yes, spring type being much worse than flap, but flap type does have to
be in vertical position. I would try to use a flap type. They also
make electronic valves which are 'normally closed'. These alone can be
more $ than the entire pond.

jay
Wed, May 7, 2003


--

Legend insists that as he finished his abject...
Galileo muttered under his breath: "Nevertheless, it does move."