...Why shouldn't I just mix my rinse in the tank like a portable instead of using a mix jug?
Depending on what you use .. I know a guy that puts his detergent in his 55 gal barrel fresh water and theres a slime that grows along with what looks like maybe mold .. not sure but Im thinking thats probably not good.
I knew another guy running a detergent thru his pump causing failure due to build up without descaling.
I know another guy that pours his rinse in the fresh water tank with no problem ever running thru his pump.
Ive experienced chemical meter failure one too many times so I add to the fresh tank as well.
Id say yeah add your rinse agent to your fresh tank and if you want water rinse only, then bypass the fresh tank by going direct using quick disconnects for tile cleaning. Also flush your pump with your bypass set up to be on the safe side at the end of the day.