"Sudy Nim" writes:

Is it better to have the check valve located at the base of the pump
near the inlet or further away on the discharge pipe above the pump?
Also, would two check valves be of advantage, one at the base another
a couple of feet above the base? TIA

One valve up, outside of the pit, is what you want. ANd don't forget
to drill a small air relief hole drilled in the discharge pipe an inch
above the pump angled down int othe pit. This prevents airlock.

You don't want the checkvalve screwing right into the pump. I recall
reading that explicitly in instructions, though I have to confess i'm
not entirely sure why. It may be that it prevents the inclusion of an
air relief hole, dunno.

--
Todd H.
http://www.toddh.net/