thanks to everyone who answered my first set of questions, heres the next batch. so we have decided to do powerwashing, and i just picked up a delco force 5 PW. 5gpm, and it has the hot water option. we are also going to use a 4 gmp machine as well so we dont run either too hard. just purchased another 16' tandem axle trailer, and 2 400 gallon tanks that will be mounted to the trailer along with all the other attachments and tools. so here are my questions: how do most of you go about adding chemicals to your washing. my idea was to pre-mix one tank and leave the 2nd tank clean water. then do a re-fill of mixed chemicals at the next site. i have read of people using pumps to add chems. as you wash. ideas? best ways? 2: next, does most everyone use chemicals when they wash all or most surfaces? almost everyone locally, including the suppliers, say dont use chemicals unless you are removing something specifically. however, when i talk to people online, or do more research, almost everyone uses chemicals. 3:i know when to use varying pressures on surfaces, and that gpm trumps psi when cleaning homes and such, but do they make a pressure gauge for your wand? the reason i ask, is that i would like to develop this far enough to be able to tell my guys what pressures to use on what surfaces, and not have it be such a guessing game. thanks again to anyone who can help me out.