I'm having difficulty picking out a water system. The Kent Marine RO system says it removes 90-94% of tap water contaminants. It has a TFC membrane, a one micron pre=filter. For $30 more you can get a high silicate removal membane, Then add another $20 and you get a RODI system. We have gone from $139 to $159 to $179. We hope to eventually have a mini-reef system with easy to moderate corals. We will never have corals that require metal halide light. We don't want to skrimp on necessities, however we want to conserve expenses where possible. Suggestions welcome.