Simple operation - Timestrip tells you when to change the carbon filter. Access door stays in place while changing filter. Carrier for filter keeps your hands away from dirty cartridges and virtually eliminates drips on floors and furniture. Submerged motor requires less maintenance than previous external models Scientifically engineered water flow - Rounded shape creates circular flow that prevents sediment from forming in bottom of system chamber. Water is forced through new multi-density carbon filters that suspend the carbon for greater contact and improved filtration. New non-clogging bio-scrubber forces all water to flow over its entire surface. No bypass is allowed. The bristle design provides more surface area for biological conversion of toxic ammonia to harmless compounds.