ro/di (runnin waste through 2nd di)

[NWhoric]

I am going to order an ro/di unit from http://www.thefilterguys.biz/ro_di_systems.htm
in the next few days. they say u cant run the waste water through a second di unit but others say you can. what does everyone think?

[mbbuna]

if you ran the waste through the DI it would be like running the unit with the RO membrane removed. the DI will remove a lot of what you want removed but you will need to replace the resins constantly. i think you might be misunderstanding what they are saying. if you want to add a second DI you need to add it right after the first DI

[NWhoric]

thanks for some reason i thought someone said that would work but ohwell. whats the point of having the second DI unit then? the first one should remove all the dirt and stuff. im going to buy a booster pump after a few months of use to make sure i need one. what pumps are good? i cant remember the name of i the one buts its the one that just runs off the water and increases the preasure somehow. i thinks its called a permanate pump.... somethin like that....

thanks again everyone

[stdreb27]

The reason for the second DI is efficiancy and redundancy. If you have two then you when the first one ones out the second one will start cleaning. And catch the crap released from the first one. They clame that the first one will roughly clean the water and the second one will finish off the deal. But I don't know how true that one is. I always thought that once the DI was spent then it starts leaching the stuff back into the water. Personally I have one of their systems, and have 000 ppm without the second di and have had that for a looong time.

[AZDesertRat]

You cannot run waste through a DI, it will be exhausted very quickly since the waste stream is 20 to 25% higher TDS than the tap water was to begin with!
The reason for dual DI is better final water quality plain and simple. Depending on how good your tap water is, how well your RO membrane works (rejection rate or efficiency) and how much water you make your DI may last a short time or a long time. The worse your tap water is and the less efficient your membrane is the shorter your DI will last and the crappier the final water quality will be. There are things that do not get treated well with RO or even RO/DI if it is not designed properly. Nitrates, phosphates and silicates are three big ones. They can be present and not even register on some TDS meters! If you have a dual DI and you pay attention to the flow rates and TDS going in and out you can be pretty sure you are treating everything the best you can. Once you start to see any TDS reading at all from the first cartridge in line, swap the second one to the first position and add a new one to the second position and you should have great water. Thats with normal DI. Some companies like Spectrapure blend and sell special resins for specific water quality problems and they are only used in certain positions, a case in point is the MaxCap cartridge which is a roughing filter or DI prefilter if you may. It is designed to make a downstream cartridge last at least 3.5 times longer than it would if you did not have the MaxCap. I went from 150 gallons per cartridge to 630 gallons per cartridge myself using the MaxCap system.

[NWhoric]

ohh ok sounds like some good info there. i ordered the single DI unit cause my water at home is not very bad. were can i get the maxcap and does it just replace one of the filters that are already in teh ro/di unit?

[AZDesertRat]

The MaxCap can be found at www.spectrapure.com , or in the sponsors section as they are one of the Reef Central sponsors.