I intend to replace the 5/16" O.D. copper drain lines on a Waterous pump with plastic air brake line. Is 5/16" O.D. sufficient size or should I try to use 3/8" O.D. tubing? I know that I can't change the ports on the pump castings, but the large line seems to me would be less likely to plug. Our water has a verrrrrrrry high calcium content and lime buildup is considerable. It is hard on valves, o-rings, gaskets, and especially pressure governing systems. Perhaps someone has a super dooper water conditioner that they are not using.