Petes Car Wash,
Specialty Equipment of Mpls-St. Paul, MN area .... before they left the car wash world ... had a nifty powder
soap tank - combo wax tank with a screen etc above the
soap side where it would be held liquid below. It also has a port for pH triggering so the
soap could be kept at the same consistency. It would mix smaller amounts as needed when the pH sensor would tell it. Sheldon Russell actually did do a good job of inventing that IMHO. We improved on it so we can easily switch from liquid to powder but still use the same pH sensor.
I would think that the other manufacturers have something similar &/or possibly better??? It is possible some distributor still sells that specific dual purpose rectangular tank???
Not sure ... but it seems like the pH sensor trigger control setting could be adapted to any car wash powder including Simoniz.