"BenignVanilla" m wrote in
message ...
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?

No, the height at which water gets pumped up to is from the water line. The
pressure of the water in the ponds takes into account the part of the run
that is below the waterline. Friction of the 4 inch pipe may or may not be a
factor in the equation: If your VF is gravity-fed from the 4 inch drain,
then it's not a factor at all. Even if that's not the case, unless you are
pumping a lot of water there probably isn't much friction going on in a 4
inch pipe.


--
David Pochron