I am not an expert on all the different resin types
- Strong acid cation resins
- Weak acid cation resins
- Strong base anion resins
- Weak base anion resins
- Specialty resins
the systems they are implemented in or what you are using your system for. I have owned the CR system reviewed above for six years and have used a Culligan commercial system at work for over 18 years to generate DI water as a quench media for aluminum ageing.
The resin in these systems cannot be regenerated by salt, it works completely different than a water softener and uses completely different resin. DI resin can be regenerated through a process that requires the use of acid and because the resin is so much smaller internally "as you stated earlier" Microorganism/algea/bacterial growth" plugs the resin and at best once regenerated it is only 70% as effective as it was when new. This is also the reason it has shelf life, and that really doesn't change by draining it, it would need to be dried and I am unsure if that would damage it. i have purchased cheap resin in an effort to save cost, this resin was regenerated and in one case only produced a third of the DI water the new resin produced. It likely had been regenerated twice.
Running "soft water" into a DI system has no effect on the longevity of the resin. The system does not care if it is hard mineral or soft mineral it is still a mineral. If you have a TDS meter measure your hard water versus your soft water the number will be almost identical.
After trying many different things, including the tubes the OP posted about, I resigned years ago to just buying new resin from a reputable source. CR spotless themselves has an exchange system that suits my needs because I do not use the system at my home year-round and anything larger would go to waste for the reasons stated above. The TDS for INDY water in my area hovers around 390ppm, I get about 300 gallons of DI from new resin which allows me to rinse my vehicles for about 8 months out of the year. I am moving in a few months to a home on well water and the TDS is nearly 100ppm less. I have not done the math yet but that should be very close to a 30% increase in DI water from the same amount of resin.