Difference between RO and DI water makers??????????

[nasotang00]

I was looking into getting an RO unit from Kent and read that the one I was interested in, 50gpd, will produce 3 gallons of waste water for every 1 gallon of RO water. WHAT A WASTE!! <- no pun intended. So, if I wanted to make 50 gallons in one day, I would be wasting 150 gallons of water? I don't think that is worth the utility bill cost to supply RO water to my tank. I can buy already premade RO/DI salt water at $.90 a gallon.
Enough of my gripe but I found that a Kent DI unit can produce DI water with no "waste water" wasted. What is the difference between RO and DI. Is it worth it? Both articles stated that the units removed 98 - 99% of all tap water impurities.
Can anyone tell me why I shouldn't go with getting a DI unit instead of an RO unit?
Thanks all.

 

[dirtybilge]

Buy a RO/DI unit there worth there weight in gold! I use some of my waste waster to fill my 90G fresh water and water my plants so i don't waste too much. Its well worth it for a reef tank if it Fish only buy a DI only.

 

[mullethead]

di resins would not last very long if hit with straight tap water, that is why they are always the final stage of the process. as far as waste and cost of water, your lfs has waste too. if it were not economical for them to make your water "with salt too" they wouldnt do it. your waste will depend on a lot of factors, hardness of your supply water,pressure "more pressure less waste too a point", temperature "colder water is denser and more waste", there are a few more that dont come to mind right now. not sure how much mine wastes as its hooked into the sink drain. now that you bring it up i will run a test tonight to see, its pretty cold here now(below freezing at night at least) i will post my results here if it may help..
scott

 

[ky]

An RO unit (mine at least) has 4 stages. The first one is a macro filter that filters out any large particles (.5 microns or larger). The second stage is a .5 micron carbon filter that filters out any harmful or poisonous substances, like any carbon filter would, but on a much smaller level (again, .5 microns or larger). The third stage is the DI unit, which is a highly ionic resin that binds to any chemical elements, such al Cl, Hg, F, etc. The final stage, the RO unit, uses a thin membrane to create an osmotic difference between the two sides, allowing basically only H and O to pass through, leaving you with pure H2O. A single tap water DI unit only offers the benefit of removing the chemical elements, leaving behind alot of possibly harmful stuff. I'm not saying that it's the only way to go, just explaining how it works.

 

[justinl]

What else would a DI unit leave behind?

 

[25gator]

up here in mass market basket /demoulas has a system for ro water with uv and other things its 25 cents a gallon. thats what i was told at least! <img src="graemlins//urrr.gif" border="0" alt="[urrr]" />

 

[mullethead]

okay just tested mine. 3 gallons of waste for 1 gallon of pure. same as kent claims on their's..its a 75 gallon 4 stage reef bought on e-bay new, made by waterworld..as far as quality phosphates 0 calcium 0. out of tap phosphates 9 calcium 50, at least on my tests.. i figure its working well but dont have a tds meter to verify. cost was 139.00 plus 20.00 shipping. clear canisters are a plus too. some makers charge extra.. shop around though, and research as all situations are different.
i really didnt think it wasted that much!! i'll have to think of a way to save and use it
scott