In addition to selling individually

we also sell wholesale

When the blue tank is full

The anion component is infused with a permanent pH indicator dye that changes color from blue to amber as the resin exhausts

20" DI Cartridge Refillable MiscROSystemParts In addition to selling individually20" Refillable Cartridge Clear Twenty inch re fillable cartridge. Filter filled with non color changing DI resin. Resin is a mixed bed 50% Anion and 50% Cation DI resin. Used in car wash spot free and zero TDS applications. Excellent for fish and aquarium stores. Shown with a ten inch filter for size comparison. Add this DI filter and a 20 inch slim line filter housing to our commercial pump driven RO system for awesome top off water OR if you want to