Hi Mark,

now what happens in 1 1/2 inch pipe where it supposedly gets ugly beyond the 42 gpm ? If I had over 60 gpm going through that pipe today the velocity of the water could be detrimental to the piping ?

Just looking at the smallest pumps availabe - I was aiming for about 40 gpm at 40 ft of head. Most pumps go beyond that.

Of course if I am getting more than 40 gpm today (say 60 gpm) then my new head at 40 gpm would be lower: 40 / (60/40)^2 - right ? So head at 40 gpm is around 17.8 ft ?

Patrick