Our campground (jointly with a water treatment co.) has a nice little business of offering resin tanks to campground residents on a seasonal rental. If I wanted to DIY my own tank what valve would I use to connect to my RV. Is it simply in / out? The tanks are mounted outdoors. I have seen some discussions of algae growth pertaining to white hoses and using a gray hose was preferred. I can only assume that a white hose allows sunlight to stimulate the growth. Does anyone have any experience to offer so I get it right the first time?