The way I would calculate that would be 34 tee fittings and 2 elbows to get 18 parallel pipes between two headers of equal size. That's 34*2.2+34*10.4+9.4*2. That's 447.2 additional feet. If we assume laminar flow (since we're at speculating a low flow rate) we could half that and assume that layout will cost us about the same as pumping 223 feet of straight pipe. Fittings add up in a hurry!
