ro/di unit

DMBillies

DMBillies

Active member
I know that there have been a number of posts in this forum about good ro/di units, but searching rc is next to impossible (I've actually just signed up for the premium membership, but it hasn't come into effect yet). I'm looking for a decent ro/di unit to install and get fired up so I can stop lugging the 5 gallon jugs around with me. Price at the outset is not nearly as important to me as being able to find reasonably priced replacement filters and pieces pretty easily. I need to be able to split my unit off of the washer water line. I don't think I'd need any thing more than 25 gallons per day.

I know almost nothing about this whole deal, so any words of wisdom about things to look for or to avoid would be greatly appreciated. I'd also be interested in used units if anyone has one floating around or finds a good deal in the next few days.

Thanks for any input...

Brian
 
Check out airwaterice.com. I buy all of my replacemenets from them. The RO membranes for a 50gpd are $35 and the carbon block and sediment filters are $12 and $2, resp. I built my own RO/DI, so I can't help on a prebuilt unit, but I think Walter at airwaterice has some that are cheaper than others. The membranes are high quality, so if you could find a used housing, you might be able to build one yourself. I found a 4 stage housing for sale in the equipment selling forum a little over a year ago for ery little and added it to my 3 stage. I'd recommend around a 6 stage as that's what i use, but some might consider it overkill. What I run is water in-->sediment cartridge--> carbon block #1-->carbon block #2-->RO membrane-->stage 1 of DI--> stage 2 of DI. I run two carbon filter for redundancy. I have been bitten in the past (used GAC carbon cartridge instead of block-my mistake, but it cost me my tank inhabitants when the RO membrane had something eat through it and flushed the accumulated crap into my 'clean water')... The first block is changed out as it ages and the second is put in the place of the first and is then replaced by a new one (only one repacement at a time, once you buy the initial two carbon blocks). I'm running two DI's because I have/had plans to run anion in one and cation in another, but have been running mixed resin beds in each so far. HTH
 
I bought mine from buckeyefieldsupply.com very reputable and good to work with. me helped me custom build mine as I got bits and pieces from someone else...
 
I have a typhoon 3 from airwaterice.com
I had it setup in 5 minutes. I got the tank with it and split the output under my sink. One hose is ro/di and the other is ro which fills the tank. The tank is hooked up to a faucet on the counter. Good drinking water :)

I am sure you can find units that do the same for less. I just chose this route after reading a lot of people on RC raving about it. It came with tds meter, auto shut-off, and a pressure gauge. http://airwaterice.com/c=MX32RzNN3uUJhvc6L6MirdeHO/product/1TYPHOONIII
 
I second the typhoon 3 from airwaterice.com. But get the dual inline TDS meter, it will help out alot with getting the most out of your filters. If you dont go with a typhoon 3, I would definately recommend getting a unit with a fast flush valve. These are suppose to prolong the life of the RO membrane and so far it appears to have done a good job keeping mine clean.
 
I also got the ebay unit 5 stage with 4 gallon drinking container for like $129. It has a flush valve and I addes a 2nd DI cartride for $15 extra so its a 6 stage now. Pretty well pleased with mine, my ato shut seems to be hit or miss when the tank is full it sometimes keeps making RO and flushing it down the drain unless I turn on the cols water in the sink to let the pressure off then it reconizes the tank is full and shutts off. It can be replaced though but I haven't. I am still getting 7 from my RO after running litterally TONS of water over the past 8 months and get 0 if my DI cartriges are full but I lost my replacement media somewhere...

If you could afford the better units I would do that but for $99 for the reef only deal you can't beat the price. I was real limited with budget when I got mine but it works fine for me.
 
lol...

I 4th buckeyefieldsupply.com for the 2nd time :)

I just bought $84 worth of stuff from them.

Best tip I can give you is to buy the refillable DI cartridges and buy the color changing DI resin in BULK!!!

Also... get you a tds meter!!! I can't express this enough.

Also... If you want to use this also to filter your drinking water, don't run your drinking water through the DI portion of it. You'll deplete the resin too fast and that means $$$.

While you're at it, get you a float cutoff valve. This is one of the things I just ordered... you'll love it and you'll save your floor.

Lastly, get you a large 32+gal trash can for water storage
 
Thanks everyone for all of the input.

For better or worse I went with the Typhoon 3, got the float valve, came with TDS meter (c_stowers, I'll probably add the dual in-line later because it seems like a really good idea), and got the splitter and hose adapter for attaching to my washer water feed.

Now I just need to decide about what I want to do for water containers to fit through my closet door... I can't wait to save myself from lugging around 5 gallon containers all the time.
 
:thumbsup:

That's a good choice. Make sure you get the 75 gpd membrane. The 100 gpd membrane has worse rejection characteristics (90% vs 98% with the 75 gpd). Basically the 75 gpd will better preserve your DI resin and mean lower ongoing maintenance costs.

Jack
 
<a href=showthread.php?s=&postid=8087435#post8087435 target=_blank>Originally posted</a> by crumbletop
:thumbsup:

That's a good choice. Make sure you get the 75 gpd membrane. The 100 gpd membrane has worse rejection characteristics (90% vs 98% with the 75 gpd). Basically the 75 gpd will better preserve your DI resin and mean lower ongoing maintenance costs.

Jack
Click to expand...


Agreed.
 
I thought why not a membrane is a membrane and filters are filters. And for the most part this is true. Building a RODI unit is really not rocket science.

When I received the unit, I installed it, and was making RODI water in about an hour. The installation was easy. The output was lower than I thought it would be, the unit was supposed to be a 100 gpd. and was putting out about 60. I did not get to alarmed; my water pressure is at the lower end of spec, 40-45 psi.

About a month went by and I had to know what the TDS output was. I bought an inline TDS meter and hooked it up. I saw 500 in and 30 out. I thought, with a DI canister the TDS should have been around 6 to 0. If the system was shutdown by the auto shutoff the TDS would clime to 150. It would take about 32 oz. of water to get the TDS back to 30.

I bought a set of gauges and installed them, one in the input of the sediment filter and the other in the RO housing. When the system was running the pressure on both of the gauges were even, this indicated that my filters are not plugged. I tested for chlorine with a pool chlorine test kit and found 0. This was not acceptable and I was not going to stop until the TDS output was 0-6.

Thinking that I must have had a damaged membrane, I ordered another one. While waiting I found a page on the web that talked about TDS Creep. TDS Creep is solids moving to the output side of the membrane when there is pressure on the output side. This happens when the auto top off shuts the water off. Okay I figured that I was going to have to live with the TDS Creep and am going to have an extra membrane.

After I ordered my unit I found that another was offered with dual DI canisters. These canisters are clear with blue ends. They are not similar to the standard canisters found in systems like Kent. They are refillable which I thought and still do think is a good idea. I had to order another filter kit to get the other DI canister. I installed it and found no difference, still a TDS of 30.

I then hooked up my output TDS sensor to the output of the RO membrane and found no change. This is it. The DI resin that came with the unit new is CRAP. It was not removing the rest or any of the solids.

I went back to EBAY and ordered 1.5 pounds from H20Slash. They are fairly close to me so if their stuff is CRAP, I could knock on their door. I emptied the canisters and refilled them with new resin. Fired it up and the TDS output was 0! It is even 0 when the system is shutdown, no TDS Creep is showing up after the DI canisters.

Message here is, do not expect the little guys with the no name product to do research and development or even quality control. The unit I have is not a non workable unit. It just had CRAP for DI resin.


What I bought $99.50, with shipping.
96845RODI.jpg


What I should have got $103.49, with shipping
96845Other_RODI.jpg


What I have now. Priceless, with shipping
96845MY_RODI


If you do get one of these units order the resin from H20Splash and dump the new stuff. Its about $19.00 shipped. http://cgi.ebay.com/Color-DI-Resin-...1QQcmdZViewItem
 
Both of those DI chambers will not work as efficiently as a single full sized vertical DI chamber. Also, the membrane in that unit as evidenced by your own TDS readings is not an efficient membrane. If you get the 75 gpd dow filmtec you get 98% rejection which with an input TDS of 500 would be an output TDS from the RO (before the DI) of around 10. That ends up really saving your DI resin -- so the membrane is important...
 
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