The units are all very similar but the cartridges are what cleans the water and I have found certain filters to work better for me, I also added a stage with parts from
BRS to have 2 Carbon blocks after watching their video on Chloromines. This combination of filters I change out every 3 months, but I go through about 200 gallons per week of Zero TDS water. I also have my resovoir set up with Tunze RODI controller so it only turns on when my reservoir is down 50 gallons to reduce TDS start up creep from wasting my DI and this is why you should never run your RODI directly into your tank without a reservoir. I get my Spectrapure filters from MD when they have sales, membrane came from Spectrapure directly and all the parts to add on, Carbon, and pre filters come from
BRS. The filter choice is what makes a great system as most of the manufacturers are using similar parts. I use the waste water to top off my pool.
The Membrane is the heart of the system and you should be getting low TDS coming out of membrane or you will kill the DI
I run the Spectrapure 99% membrane and this is the workhorse of the system, my membrane is over a year old and yet I have 4 TDS out of membrane going into DI.
http://spectrapure.com/NEW-99-percent-rejection-SpectraSelect-Plus-Tested-90-GPD-RO-Membrane
I run 2 DI cartriges also from Spectrapure 1st the MaxCap Super DI then the Silica Buster Super DI color changing. These are not refillable, but they are larger and last longer.
http://spectrapure.com/FILTERS-MEMB...GES-RESIN/MaxCap-DI-Cartridge-SuperDI-10-inch
http://spectrapure.com/FILTERS-MEMB...DI-Cartridge-Color-Indicating-SuperDI-10-inch
This is very important to add second carbon if your water company uses Chloromines!
I have run the Chloroplus 10 Chloromine filter, but recently changed to
Bulk Reef Supply Universal Carbon Block X 2, run in series these keep chloromines out of my water.
.
http://www.bulkreefsupply.com/brs-universal-carbon-block-filter-1-micron.html
I run the GE Rosave Z prefilter from
BRS, I run the 1 micron version.
http://www.bulkreefsupply.com/ge-rosave-z-depth-sediment-filter.html
If you have low water pressure anything below 60psi you should run a booster pump, low pressure does not allow membrane to function properly and it will not be able to reject 99%.