I have had the UHE for just over two years now and it is amazing. Yesterday I ordered only my second replacement MaxCap DI cartridge! The unit was installed in March of 2008 and it still contains the original SilicaBuster DI cartridge from day one. Pretty amazing considering I have two tanks, a 100G full blown SPS reef with a 30G sump and a 16G nano reef stocked with softies. Water here in Phoenix is pretty hard and high in TDS, often over 800 in my location and never under 500 and I make a lot of water between the 23 gallon autotopoff reservoir and my five 5G water jugs for water changes. I checked the UHE on Saturday while doing some tank maintenance and found the following: Water temp 78.1 Water pressure (tap) 68 Water pressure (booster) 90 Tap TDS 552 (using my COM-100 handheld) RO only TDS 3.2 MaxCap DI TDS 1 (using the inline probe) 2.1 (COM-100 handheld) Final TDS 0 on both the inline and COM-100 I have only replaced the prefilter and carbon block one time in the 26 months and there is still no appreciable pressure drop across the filters and no chlorine breakthru using a low range CL2 test kit. I have a set of spares but have been monitoring things to see when they will be needed. Since you only run 2/5 as much water through the unit everything lasts so much longer. Between the water savings running at 1:1 waste ratio, the filter replacement savings and the huge DI savings the unit is well on its way to paying for itself! I would buy one again in a heartbeat.