Originally Posted by
aquaguy24
http:///forum/post/3096124
Does the gpd rate really matter. Is the water better filtered cuz it's mvng through the filters slower. Just something I've always wondered. Anyone ever did a test with a TDS meter. I have a coralife 4 stage 50gpd unit that I'm very happy with. $155 shipped.
Technically yes it does matter/there's a difference. The slower the gpd, the higher the rejection rate on the RO membrane is. Meaning more waste goes down the drain, and less, but cleaner water enters the DI stage, causing the DI resin to last a longer time. Something along the lines of a 150gpd unit may have a TDS reading of 30 coming out of the RO, while a 50gpd or so may have TDS in the low teens or single digits, using the same feed water.
Agreed that most already built units are the same, just with different labels. The only thing is get a unit with at least a 10" vertical DI chamber. The cheaper units with the sideways DI cartridge mounted on top of the unit are cheap and ineffective. You can't pack DI resin tight enough for horizontal use.
Some other important things to know is your local water supply. If you chlorine or more probable, chloramine. It's very important to the RO membrane to hav a chloramine carbon block as one of the prefilters (usually the last). Doing so will greatly extend the life of the RO membrane. It's also important to know the micron ratings of your sediment prefilter (the first one). The small the bigger, but life will be shorter. I suggest going with a 1 micron. If you want to use a .5 micron, use it in the 2nd prefilter spot, and use either a 1 or 5 micron filter in the first prefilter slot.