As I understand it, you count the entire run, length and depth from the
intake to the outlet...then add for the friction of the pipe and fittings.
Someone has info about it on their web site but for the life of me I can't
remember the url.

"BenignVanilla" m wrote in
message ...
My main pond has a bottom drain...which feeds a 4 inch pipe up to the VF.
When calculating the head do I need to consider the depth of the bottom
drain and calculate from there? or do I calculate from the water line?

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BenignVanilla
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