copper will be better because it won't corrode,even with a dryer i'd suggest a drain at the low spots in the run. And what ever you use make a larger central manifold and take your run off it-it will have less pressure drop at the end. But above all, consider the way you run it. Keep it as protected as you can,and drain it and your tank on a regular basis. I took a drain off a truck that has a cable on it -that way when you drain tank you don't have to bend down or possably get dirt, etc. in your eyes-good luck, jimmy.sorry bout being so long winded..