I have a similar setup, using too rubbermaid trash cans for my system. 1 can is used to have the RODI fill then I pump it into the second tank where I mix my salt. I keep both tanks heatd to a desired temp that way the water is always similar to the tanks I would use the water in. I also keep up with Salinity in my salt tank of course. In addition I also keep a pump in the salt tank to keep the water circulatign adn help with the mixing. I do check my tds in my first tank to make sure I know what its coming out of my RODI system. Yes there is a meter on my output of my RODI i just like to make sure.