(It was never used and is no longer needed. :-) See pictures, and my instructions below for more information.
Envig CarShine 817 Deionized Spotless Car Wash System w Bypass Valve & TDS Meter
Envig CarShine Deionized Spotless Car Wash System with Bypass Valve, DI Filter
The Clean Garage Spot Free Wash System 50 | Deionized Water DI Rinse | Bypass
Spot Free Car Wash System 50 | Deionized Water DI Rinse | Bypass Head | TDS Incl
Unger Professional Rinse'n'Go Spotless Car Wash System No TDS Meter