View Full Version : RO vs DI question.


olds350racer
08-02-2007, 11:26 AM
Besides the excessive use of filter media, is there any reason you could not use a DI filter without the RO system (assuming the end result is 0 TDS)?
Thanks in advance for any input.

ouling
08-02-2007, 11:36 AM
the water would have to pass through the unit extremely slow, and the DI canister would need to be 3ft long. My lab room use those and they dont make water that much faster than RO/DI units.

MattTVI
08-02-2007, 11:43 AM
Besides the excessive use of filter media, is there any reason you could not use a DI filter without the RO system (assuming the end result is 0 TDS)?
Thanks in advance for any input.

no reason at all, in fact, some folks hate the "waste" of the RO/DI system and use DI only systems, there's a quality one called the Kati Ani or something like that...

it seperates the DI resin, most RO/DI units come w/ mixed bed resins, the seperate resins can be recharged, so you don't have to buy more resin (at least not for a while)...

here's spectra pure's version (http://www.spectrapure.com/St_di_systems.htm) of di only...

olds350racer
08-02-2007, 11:58 AM
Thanks for the input. I just use a cheapo DI filter, but because my TDS from tap is not too bad, the filter seems to last for a while and I my TDS is at 0. I'll have to check out the seperate resin path though.

Schwaggs
08-02-2007, 12:59 PM
I agree with the others, the main reason people put RO before to the DI stage is to remove the majority of the impurities so that the DI resins last longer.

olds350racer
08-02-2007, 3:16 PM
That was my understanding as well Schwaggs... but never hurts to double check. :)

Roland Jacques
08-02-2007, 8:29 PM
DI only is fine for small amount of water use. Like you say our water is very good out the tap.
But if you do the math it cost a LOT more $$$ per gallon. If you only need 100 or 200 gallons a year it not that bad of a price to pay. (Recharging resin has it own set of issues)

Be sure to use a very good carbon filters before your DI only system.
Id recommend at least one .5 micron 20,000 gallon chlorine guzzler. Otherwise chlorine will exhaust your resin VERY VERY FAST!!