Both KR & Nat'l Pride use the reverse hookup solenoid banks that relies on sensitive draw of shampoos etc. We are somewhat OK with that in our set up as long as we make sure our plastic tubing stays extra supple & not allowed to get old. They were both nice enough to sell me on a component basis since I had my two tubs locally fabricated. Trent from Nat'l Pride came through for us in explaining the perplexing (non conforming?) delivery system. I still have very high regard for him to this day because of his willingness to do that for us!!!
We would be open minded to a better way to deliver the shampoos to the sprayer tool as long it did not take up too much increased space & too many more components. That kind of delivery is in reference to what MEP001 stated if I read his post properly.
My competitor's 5 Evolution Dog Wash Portable Units may or may not have a better delivery system ... I was hoping that a fellow forum member could comment??? On their website advertising they describe themselves as the industry's "GOLD STANDARD"???
https://evolutiondogwash.com/