Thanks for the info on TDS, I also have a float/solenoid set up - it is great! My can is a heavy duty rubbermaid 45 gal trash can used commercially. It might spring a leak in a few hundred years I guess. I purchased it at Lowes, maybe Home depot for around $30.
What TDS level do most cp's tolerate? As a former aquariast I think in terms of water hardness, is TDS similar?