Help me select a SpectraPure RO/DI Unit

[Biokabe]

Now that I finally have the means and the space for it, I'm finally taking the first steps to upgrade my reef tank. To go along with the new tank, my Mighty Mite RO/DI system will be replaced with a shiny new (or refurbished, I'm not proud) SpectraPure system. Since the current reef can definitely benefit from the new unit, I'll be picking it up in the near term. The problem is, I'm far from an RO/DI expert, and I don't know which one to get!

I'm currently considering one of the following three units:

http://spectrapure.com/RO-RODI/RODI...ROD-5-Stage-90-GPD-RODI-System-with-Double-DI
http://spectrapure.com/RO-RODI/RODI-SYSTEMS/CSPDI-Manual-Flush-90-GPD-RO-DI-System
http://spectrapure.com/RO-RODI/RODI-SYSTEMS/MaxCap-Manual-Flush-90-GPD-RO-DI-System

I'm willing to spend on the MaxCap if there really is a lot of value there, but at the same time I don't want to pay extra for more "oomph" than I really need. Judging from the city's water quality report, the water here is already pretty good - TDS at less than 100 - and my home's water pressure sits at 100 PSI. So, if the refurbished unit is going to be just fine, I'd just as soon pick up that. But if I'd be a fool to not get the MaxCap, I want to know that too. Unlike with my first tank, I don't want to compromise on the initial purchase to save some money and then end up spending that money and more later on when I finally give in and pick up what I should have purchased to start.

A second question - is there any reason I couldn't eventually replace one of the DI canisters on the refurbished system with a MaxCap canister?

 

[cromag27]

First of all, forget the four stage, you want a five stage. the maxcap comes with an extra inline tds meter and the filters are a lot better than the refurbished one you linked to.