Quote Originally Posted by Martinm210 View Post
So is this a closed loop or something like a bong cooler?

If its a closed loop the climb does not matter (energy lost in lift is returned on the down return) Potential energy is essentially canceled and can be ignored.

Also the 12 feet of tubing is a minor loss and can also be ignored for the most part. In a closed loop, a single D5 would even be plenty let alone two. An open system like a bong cooler is different though...there you do have to think lift, because the energy on the shower down is in the open air and completely lost.
What pump would you recommend for an 8' bong cooler?