anyone know anything about this? i just found this on a site
A De-Ionization Tank (DI Tank) is filled with a mixed-bed of resin beads that are positively and negatively charged. The Total Dissolved Solids within typical tap water have either a positive or negative charge. As the tap water passes through the DI Tank (or DI Cartridge) the dissolved particles attach themselves to the oppositely charged ions and stay within the DI Tank (or DI Cartridge). The finished water continues on, 99.9% pure. Depending on local water hardness a DI Tank (or DI Cartridge) will become saturated after a certain period of use***. The resin can then be regenerated in the DI Tank almost to its full capacity making the use eco-friendly at a fraction of the cost of new resin. To monitor the saturation point a DI Monitor is used. A small probe, screwed into the head assembly of the tank and connected to a purity light, gives an instant read-out if the water is good or is in need or regeneration (or replacement, if cartridge system in use).
See diagram on DI Y connector (next)