Why 30 PSI?  The basic emitters say rating is at 15-20 psi and they are good for gravity systems.  Does it end up watering the bottom of the hill more than the top?  Probably only 6-8 ft elevation change and I can put the tanks so it is split 1/3-2/3, which would help if mainline capacity could be an issue.  I could elevate the tanks(275 gal chem totes) a few feet on a stack of pallets, but that's not getting me much more PSI.  Not questioning your experience, just curious.  Hose is a possibility and maybe a better option, but it's a few hundred feet and don't want to have to string it out, timer, no pressure tank so the switch needs to be flipped, etc...  Thanks for the responses.  Ben