RO/DI, RO, or DI?

[malulu]

Hi,

I have been using this for my aquarium GE - Model GXRLQR - Lead/Cyst Quick Change Refrigerator Filter  (Yes, please go ahead and laugh)  :-[

and now i am sick of it, and get ready to put in a pure water for the aquarium, and i did some research about RO/DI, the only concern i have is:  RO/DI unit have a lots of waste!  about 1:4 ratio (meaning each 1 gal of pure water produced will have 4 gal of waste water down the drain...) this is insane!!!

in order to achieved no wasted or minimum wasted approach (http://www.wetwebmedia.com/rofaq2.htm)

- some suggested, by using RO only unit will be enough for aquarium if the town water is not too bad (i am in GreenBrook, NJ 08812 - next to BridgeWater)
- others suggested just go ahead use only a two column DI units or Rechargeable DI unit...

so, any comments or suggestions? Please help to comments.

Thanks and Best Regards,
David

 

[RichT]

All the waste is generated from the RO membrane. So RO only will generate as much waste as RO/DI. A few suggestions, which I have implemented, will reduce the rejection rate. Warm the water, booster pump, and permeate pump. I would guess I'm closer to a 1 to 1 ratio then a 2 to 1 at this point.

 

[malulu]

when they said RO only, mean only use RO, all the output use as pure?
how do you warm the water - the water is straight out form the pipe to the input jack of the unit?
thx

 

[blange3]

David,

I warm the water by using a mix of hot and cold water as the input from a faucet connetion instead of using a saddle valve to the cold water pipe.

Rich, can you explain a little about the workings of a permeate pump? This caught my attention during the AWI group buy, but I never did the follow up research.

 

[RichT]

Bill,

From what I understand. It uses the energy from the waste line to force more water threw the membrane. The pump actually stops the flow from the waste for a couple seconds then there is a surge in the product water when the waste starts again. Some how or another it's suppose to help prevent TDS creep as well. I don't know/remember the specifics but it has increased the output with no additional TDS showing on the meter.

HTH

 

[blange3]

Thanks Rich,

It makes sense. I might give that a try next AWI buy.

 

[malulu]

thanks for Rich and blange3 's reply...

anyone have comment on the "Rechargeable DI unit"?
thx

 

[Jcurry@wesketch]

I bought a used RO unit a couple of years ago & the guy had installed a valve on the waste water output to create more back pressure on the RO membrane. I can't tell you if worked better or not I have nothing tp compate it to.
You may also want to look into a Kold Sterile unit
http://www.poly-bio-marine.com./
There have been a few threads about them:
http://reefcentral.com/forums/showthread.php?threadid=11235&highlight=Koldsteril

The biggest complaint about them (other than intial cost) is the availibilty of replacement filters. But they are located in West Orange NJ so you drive over & get them if needed.

Also don't forget that the waste water is no more polluted than tap water so you can use it for others things if you save it.