At 05:30 PM 1/8/2007, Pensioner wrote...
>and about 5" or so up each side of the "U".  Noticing that the water
>level
>in each side of the U is essentially the same, mark the tubing with
>some
>tape at the water level on the open side of the U (not connected to
>the
>tank).  Put another piece of tape 11 inches +/- 1/16" above this
>mark.  You
>now have a 11 in-H20 calibrated tool

Not quite. 11" pressure is an 11" differential when measured with a
manometer. You should have enough of a "U" so there's always some water
on the "low" side. If the water goes up on one side by 11", the other
side will lower by 11". Your description will result in a pressure of
22" H20. You want to make a mark at 5.5" above the static level, which
is the same as an 11" differential.