Hey guys im really liking the site and all the information and help that is on it. I'm looking to build a simple aoftwash setup for rooms only. I current have my pressure washi g rig that consist of 200 gallon tank and Honda 4 GPM with 200' of hose. I was looking to get another tank of 100 gallons with a pump and hose...maybe fatboy pump , I want to keep it 12v setup. Im familiar with sh mixtures and so on. My question is I was only thinking of getting that 100 gallon tank and keeping my mixture in that and having the pump connected to that tank and also my fresh water tank with a ball valve to clean the pump out when done and to do rinse on the roof. My local supplier is telling me I need 2 tanks one for straight sh and another for sh mix???? Why... i rather ask here but i feel like they are taking me for a ride. I don't see why I would need 2 additional tanks on top of the one I have. Then someone else who work there said i can do it all with my pressure washer with down stream injector. "Just fill your 100 gallon tank to about 60 gallons of straight sh and injec after the pump". Now i have done stuff like that for houses and concrete, when the chemical doesn't really have to be precise. I asked what will my mixture be then? The answer I got "strong enough to clean a roof"...really. I always thought that your mixture gets diluted when it travels through the hose after the injector and that's the reason why I'm looking at getting a single 100 gal tank with say 70 gal water and 30 sh for a simple wash. Can you guys share any correct adviceI would really appreciate it also which pumps you would recommend.