I loaded this windows101.com bulk resin, bought 2/14, and used it for the first time today. The TDS meter read 220-225. I let the water run for about 10 minutes. The TDS meter dropped to 160-165 after about five minutes and stayed there. Remember, you are supposed to change resin when the TDS meter reads 20.
Fortunately, we had a nice rain shower while I was washing the car, so it got an automatic soft water rinse.
Operator error! I did not have the unit assembled correctly, which allowed the water to bypass the resin cartridges. TDS = 000.
BTW, The Windows101 resin was $115/cubic foot last February. It is now $160. CR Spotless resin is $215/cubic foot. Shipping from Windows101 in Seattle to south Florida was $58.
1 cubic foot = 3 refills of the 20 cartridges.
I figure I get about 20 rinses (rinse only, not wash and rinse) per fill. So...each rinse is ~$3.00.
The with vs without spot free rinse step when washing my GT is very pronounced. With the spot free rinse, it really does not matter how long I take to dry the car, it does not spot. On my truck, I dont bother drying at all other than blowing the excess water off with the air hose.
I tried it first with store purchased distilled water in jugs before purchasing the distiller. Try it, it only costs a few bucks for a few gallons of distilled water to try. Then if you like the results, decide on resin based or distiller. The resin systems do have some convenience as they are 'on demand' where the distiller makes the water ahead of use, far too slow for on demand.