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Discussion Starter · #1 ·
I know that some of the great minds on the boards here work with large scale systems. I have been doing some research on EDI or ElectroDeIonization. It seems to run in conjunction with the RO system and gives DI water at about 17.3 meg consistently without having to exchange resin. Has anyone had experience with this equipment? Is this true? Thanks for your input.
 

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spaceman spiff
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Can't say I've heard of it, to be honest. What does 17.3 meg mean, I'm not familiar with that term regarding water purification.
 

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Discussion Starter · #3 ·
Water purity reaches a point where it can't be measured by tds or toc. It is then measured by electrical resistivity. Meg. is shor for Meghomn. High end industrial systems like pharma and bio-science use this for producing medicines, cell culture growth studies and such.
 

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Discussion Starter · #5 ·
I agree completely. I meant the question to be posed to those who work in the commercial/professional arena. I was hoping to find someone that worked at a large aquarium or maybe pharma. Sorry if I wasn't clear.
 

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There was somebody on one fo the boards I frequent that worked in a lab and used to get his water from there for his tank. He stated that it was the most pure water you could possibly get and I believe he was talking about this process. I will try to jog my memory and have a look around to see if I can locate him and ask your question.
 

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Discussion Starter · #7 ·
Thanks for the help. Happy Sunday, BTW, the coffee's on. :dance:
 

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Okay, here is the reply that I received about EDI.

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I do know that electrodeionization is used for large-scale treatments like for industrial applications. The electro component is used to help clear the membrane, rather than have to clean or replace it as often, which is good when you need very large volumes filtered. When I was doing my PhD, we needed quality beyond what you get with just R.O. so what we had was a RO/DI machine that was fed with distilled water. The water then went through R.O. filters then through the deionization cartridge which is called "ion-exchange" to get to the gold standard "ultrapure" quality of 18 megohms (which is totally unnecessary for aquarium use). The company that made our filter- and just about all the filters I saw in other labs is Millipore, and the unit we had was one of their "Milli-Q" units. I think they make a few grades and may have one appropriate for home use, in which the incoming feed is tap water- If someone really wants RO + DI, they can get a unit like this- it will cost them.
Here is what I think: For hobby use, RO is all you need, and I would only do D.I. in addition to RO, not as a substitute. Be sure to replace the RO filters as needed, and to get decent grade filters. I would be suspicious of any deionization unit, electro- or not, that can be run as a stand alone unit without prior RO filtration. I doubt such a unit will match the quality and convenience of RO. Therefore, I don't think it's necessary for our needs. If someone really, really wants to do a post-RO filtration, by all means, do D.I., but I would stick to the tried-and-true ion-exchange cartridges which are designed for volume outputs like we need, rather than go with a electrodeionization unit, which is most certainly more expensive for a real one, and not necessarily better.
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I hope that gets you a little closer to what you were looking for.
 
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