The Indion mixed bed ion exchange resin is a mixture of highly purified, super regenerated strong acid cation and strong base anion resins in a 40:60 volume ratio. It is recommended for any non regenerable mixed bed applications where reliable production of the highest quality water is required, and where the resin must have an absolute minimum of ionic and non ionic contamination before it is used. Any precontamination in the resin is only reducing the amount of time you can use your resin for, so a higher quality resin will last you for longer. This mixed bed formulation is regarded in the pure water industry as the best performing mixed bed de-ionisation resin, consistently outlasts every other brand, pound for pound.
MB-151 resin is specially formulated for hard water areas. Regular resin (MB-115) would become a lot less effective very quickly, as the contaminants in the water would wear it out a lot faster. MB-151 meanwhile is designed to function correctly even with the worst possible water qualities. It can also be used in areas with good or average water qualities without fault.