The Vertex is not a good choice, they don't last. All the big name vendors tried the low waste thing years ago and figured out it does not work long term, membranes must be flushed. This is why almost all systems use a 4:1 waste ratio and the only one which successfully does not is $800. It took years of engineering and testing to develop the Spectrapure MaxCap UHE and it is different from the others in that it uses a computer microprocessor to flush using stored DI, not tap water.
For normal RO/DI systems you cannot beat the CSP-DI on sale here for $145:
SpectraPure Customer Appreciation SALE! 20% - 50% off
It comes with a tested 90 GPD RO membrane, an absolute rated 0.5 micron prefilter so the 0.5 micron 20,000 gallon carbon block is protected, a full size 20 oz vertical refillable DI canister and cartridge, a dual inline TDS meter, an inline pressure gauge, a capillary tube type flow restrictor so you trim it for an exact waste ratio and more.
Other good choices include the 75 GPD premium series found here:
www.buckeyefieldsupply.com
The Optima seres found here:
www.purelyh2o.com
The Reefkeeper found here:
www.melevsreef.com
Ore even the Typhoon III with the upgraded low micron filters found here:
www.airwaterice.com
Watch out for most of the ebay quality systems. Many will not tell you what membrane it contains and it may be a 90% removal nano filter instead of a 96-98% removal RO if its advertised as 100 GPD or higher. They also use low end things like horizontal hollow tubes thye call DI filters rather than full size 10" vertical canisters, multiple low end carbons often with no micron or chlorine ratings, no TDS meters, no pressure gauges, high micron prefilters and more. Do not fall in the "Stages" trap, more is not necessarily better, especially if they are worthless carbons, drinking water taste and odor filters, horizontal DI's etc. Pay attention to what the stages contain and not how many there are.
You want a 1 micron or smaller prefilter, smaller is better and absolute rated is better than nominal rated. You want a single 0.6 or 0.5 micron Chlorine Guzzler type carbon block, KX Matrix is a good brand. You want a Dow Filmtec or GE Water RO membrane (Spectrapure uses Dow Filmtec then treats and tests them in house), Buckeye, AWI and Purely use Dow, Melev uses GE, almost identical in performance. You want a single full size vertical 10" canister type DI filter which can be refilled, all those I listed use those in their better systems. You need a TDS meter and a pressure gauge to troubleshoot the system and to know when the DI is exhausted, its often cheaper to get it with the unit rather than later. The capillary tube type flow restrictor is the better choice, Spectrapure and Buckeye use them standard. Things like flush valves have no proven value so only lighten your wallet. A DI bypass valve is a good thing, it allows you to use RO only water for other uses.
