DI water only

why does it matter the brand of the DI unit?

As far as I understand, the unit just holds the DI resin, and it's the resin that does all the work? Is it the type of resin that comes with the kati ani device?

Does anybody have experience with the Kent DI unit, that can give a thumbs up or down on it?
 
I took interest in this method of water purification after a friend (capncapo) told me of this method that was being discussed here. I have extreme interest in learning about this type of purification to avoid wasting so much water, especially with over 1500 gallons (soon) of saltwater.

I haven't found any articles on the specifics of just how to regenerate the resins, ie: 1) Get a big tub, 2) Pour resin in tub, 3) do this do that. Also, as far as how much resin one would need for large amounts of water production is a mystery.

I think I can probably piece together a large unit for this type of filtration, might need to get someone to craft some acrylic since Dr Foster and Smith no longer sells the kati/ani. However, there have been several concerns here that have me doubting the effectiveness of this system, ie: 1) Short life of DI resins, 2) Channeling of water through resin, 3) Uncertain purified water at end-stage unless tested. With RODI, I haven't worried about my water, it has always been 0 TDS.

If there were some industry person or company that utilized this method, it would be cool if they could chime in here with specifics about getting started, where to buy materials and what their opinion is about the purified end product versus RODI.

Just a couple thoughts.

Dave
 
good points Dave, but unfounded (as in no worries) re: your DI concerns:

1) short life on resins: Hmmm... not sure what you mean here. Depends on perspective. In terms of total lifespan... they are regenerable without building up any significant kind of memory in our lifetime :p On that point... they blow RO membranes out of the water in terms of value/ongoing expense. With regard for time between recharges.. we could make the argument that it is similar to the need to backflsuh and RO membrane. Or... do consider that in exchange for the time spent recharging... you save many hundreds of dollars (lack of membrane replacement as with RO).

2) channeling of water through resin: a non-issue. The columns are build to avoid this. And regardless... it is less of a risk IMO than irregularities in RO membranes that inevitably occur allowing various things to breach.

3) uncertainty of purified water: hmmm... if you mean the degradation before the need to recharge, again... a non-issue. Its not uncertain or even in need of testing. The resins change color and slowly at that over time to indicate the gradual exhaustion of resins. The change in water quality is so slight that its a moot point.

And again... most folks that go to DI are willing to field the recharging duties in exchange for not wasting water or money (replacing membranes).

Plus... you can run tap water through a DI a lot faster than you can an RO. A small perk to not have to wait so long for purified water.
 
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I have just a couple of things to add to Anthony points:

1.) My Kati-Ani 2 unit is about 8 years old now and still going strong.

2.) I have never had any channeling issues in that time either.

3.) The color change in the Kati-Ani is unmistakable, in contrast to the color changes I have seen in mixed resin bed DI units.
 
FWIW,

I sent a request to Spectrapure indicating that I would like to convert my RO/DI system to DI only with seperate resins. Here is their reply:

"What you are requesting is not recommended and in the long run most of the customers that have tried this eventually revert back to using the RO./DI combination. The water purity that is achieved from using tap water DI systems does not provide the purity required for most DI water uses but you are sure free to try it if you would like to although we will not be able to provide much in the way of assistance since it is not something that we would recommend.

The DI resins that are listed in our catalog are designed specifically for use in RO water and not recommended for tap water. "

Thank you for contacting SpectraPure Inc.
*************************************************
Their site states that the resins are used to replace in Kat Ani systems????????

Color-Indicating Strong Base Anion Resin

High operational capacity
Excellent silica removal
Color changes to show remaining capacity
Use to replace Ani resin in "Kati-Ani" DI Systems

:confused:
 
Spectra pure is in the principal business of selling RO membranes.

That was their first product line.

Only when DI units became popular did they get into the resin game to compete with others selling DI and/or RO

You should not be surprised to hear this reply :p
 
Well at first I was, as their resin specifically stated for "Kati-Ani" systems which made no sense that it was "not recomended for tap water and only RO water"
I now have seen the light:)
Thanks
 
Does anyone have a feeling for how long a typical (e.g. kent or spectrapure) dual bed, non-mixed de-ionizer would go before a recharge (in gallons). I use a AquaPharmaceuticals tap water filter right now and would love to go a lot longer before either buying new cartridges or recharging. I have pretty good water, so I'd say I get about 100g or so out of one cartridge presently.

Eric.
 
Ok, now one thing that hasn't been brought up about the DI here.
IN doing search for Chloramine removal.
There surprising lack of ability to remove this common chemical in our Tap water.
apparently the chloramine goes right through DI units, at least those they talked about.
Most municipalities in the USA use chloramines.
So far in my searching, the only thing that has come up to remove this, is to use a catalytic activated carbon, and most say to put this behind a another carbon block, as put carbon block into a catalytic granulated activated carbon.. (must be calgon push behind this since they make most carbons?) but this is by other manufactures stating this as well, such as GE. So has anyone tested chloramines/ammonia after these Kati/ani resins?
 
My supplier originally cautioned me about this. It may be the type of resin choice? I don't know. But the resins offered in my area did not remove chloramine. This was considered a good thing for the drinking water, since it still 'protected' the user from the buildup of too many bacteria.

I still maintain (several posts ago), you need to know the ions the DI unit does and doesn't remove, to determine its value.
 
leebca said:
My supplier originally cautioned me about this. It may be the type of resin choice? I don't know. But the resins offered in my area did not remove chloramine. This was considered a good thing for the drinking water, since it still 'protected' the user from the buildup of too many bacteria.

I still maintain (several posts ago), you need to know the ions the DI unit does and doesn't remove, to determine its value.
Click to expand...

This is also a question being discussed in this thread:

http://reefcentral.com/forums/showthread.php?s=&postid=5329132#post5329132

I see now it has been asked in the Chem Forum so hopefully Randy can give us the low down.:) Clear the water if you will.:D
 
leebca said:
Hobster,

Another (I think) more relevant discussion by Randy:
http://reefcentral.com/forums/showthread.php?s=&postid=5345358#post5345358

I think Randy's article is clear. RO = the best. When should it be used? When the ions and neutral chemicals of your source water are not treatable by, reactive with, or missed by, DI systems.

His article:
http://reefkeeping.com/issues/2005-05/rhf/index.htm

I better know what to do, now. Thanks all! :cool:
Click to expand...
I read that discussion with Randy above. The problem is Randy is talking about mixed resin beds which require expensive replacement cartridges. That is not what a Kati-Ani system is. The recharging chemicals for my #2 system cost me less than $10/recharge and last for hundreds of gallons. Now, it does take longer for me to recharge my Kati-Ani than to replace the membrane and prefilters on a typical RO unit, but in Randy's words, "if there is a carbon and sediment filter before the DI, the only thing that will get through is very small particulate matter. Depending on what is in the water, that may be fine. It will take out most things that I would be concerned about."
 
Steven,

That is how I took Randys explaination also. (buying new resins)

What I am interested in trying is getting a regular mixed bed resin and separating the 2 resins, as per the old Tap water filter instructions. Buying the resins separate is much more expensive. If I can get them apart, I will put them in individual cartridges.
I plan on having a sediment, 5 micron and 1 micron carbon filter before the 2 Di's.Our city water produced by one of the largest RO plants in the country so it is pretty good to begin with.
 
StevenPro said:
The recharging chemicals for my #2 system cost me less than $10/recharge and last for hundreds of gallons.
Click to expand...

And this is cheaper than using RO/DI water?

Now it seems to me that assuming it is cheaper, which the numbers don't seem to support, the DI only water does let more through than an RO/DI combo, and remembering something Anthony has said before (regarding carbon use inthe aquarium) do you really want to be cheap on a vital part of your aquarium health when the savings isn't really that much? Now true for large greenhouses or other applications where you are going through thousands of gallons of water on a regular basis and need water in a rapid fashion seems using DI water would be much more benificial.

One thing I would be curious to see is you did a "refit" on an existing RO/DI system by removing the membrane but leaving in the prefilters (in my case a sediment filter & 2 carbon filters) then just put the two separate resins after, and see what the end result is and compare that to RO/Di water output.
 
Steven,

But you (and some others) are ignoring an important issue -- the quality of the source water.

The DI units, no matter how good, will deplete quicker with a high TDS source water, which = my case. The DI units remove ions. If it isn't ionized, it goes through. And finally, DI puts/adds something to the water. All three factors have to be accounted for, before a rationale decision is made.

Using over 40 gallons per day, I'm not messing with DI if it can't be cheaper and less troublesome AND removes what I need out of the water, than the RO

It's a bigger picture issue that doesn't have a 'one size fits all' solution. :)
 
I do 15% water changes per week.

I have a 300 gallon and 180 gallon display. I have a 70 gallon refugium. I have a 100 gallon sump. I have a 100 gallon quarantine tank (including sump). I rinse my labware, test kits, etc. with the water. I love ice in my drinks (it's hooked up to my ice maker). It is also my drinking/cooking water. I make my own additives with it. I sell 10-15 gallons a day to neighbors who can't stand their water and have aquariums, or just want decent drinking/cooking water. I use about 4-5 gallons a day for evaporation.
 
so where again exactly does the bypassed water of a "zero-waste" system go, again?

And what happens if the household does not use all of the bypassed water (hot water tank, laundry, etc) as when making batches of water for water changes, filling up new tanks, etc (hundreds of gallons of excess).

You do understand the principal of RO here? Its a membrane... the water that passes through it is low in TDS, the water that does not (reject or bypass) carries away much of the rejected matter (hence the hardened, multiple gallons of "waste" water)

Or am I missing something here? Do the zero-waste units no longer have membranes? :p

And if you mix a batch of 40 gallons of water for a water change... and 160 gallons of bypassed water make it to the washing machine or hot water heater... what happens to that water if you don't use it all in one day?

A better question... where exactly is all of that waste water being held on demand ?

Somebody please enlighten me. I'm sure I'm missing something about this "zero-waste" unit.
 
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