Nice try Elliot! Drive more, then let me know. :wink
The resin has an 18 month shelf life. It's not going to fail precipitously, but it tails off. Use it or lose it.
Actually the opposite, Gary. I've been using this system for about 8 years and I've noticed that once the PPM meter starts registering over 000, it begins to fail relatively quickly. Obviously depends on how much water you use.
One thing about letting water sit stagnant in the containers. You can get mold accumulation which affects the spot-free properties of the deionized water. They recommend that you drain the canisters if you anticipate leaving them unused for a prolonged period of time, especially in warmer climates (i.e. Florida).
Seeing as it's a major PITA to remove those things, I just leave them full and cross my fingers that the next wash won't be spotty. I'm surprised they haven't designed some type of quick-connect.
EDIT: From the website FAQ's (I was mistaken, it's algae, not mold):
WILL THE RESIN GO BAD IF I DON'T USE IT?
Yes it is possible. After long periods of non-use there is a possibility that algae can form and foul the resin. If it is going to set for a long period of time with out use (60-90 days) we suggest that you remove the resin cartridges, allow them to drip dry and dry the inside of the blue housings to prevent algae growth.
THE METER DOES NOT SEEM TO BE WORKING. IT ONLY SHOWS ALL ZEROS?
That is perfect, the meter will read 000 for 95% of the resins life expectancy.
Once you start to see numbers, it will increase rapidly.