Question About Ro/di

Tank Predator

Tank Predator

New member
im looking into getting one is there anything i should be avoiding or a certin kind i should get ? been looking on ebay for some and i have really only found some kent marine ones any input would be great

thanks
 
the ebay units aren't as good of a deal as you think. a lot of them don't use true RO membranes, they use micro-filters. ro membranes of 75gpd are the most efficient (Dow filmtec is the best) and can produce water with a 98% rejection rate. so if your tap water has a tds of 100, when it comes out of the RO the tds reading will be 2. thats abut as good as it gets and your DI can easily remove the 2tds. micro-filters and RO unites over 75gpd (most over 75gpd are micro-filters unless your paying big bucks) generally have a rejection rate of 90% or lower. so with your 100tds tap water you now have a 10 or 15tds after your RO and your DI has to pull out so much more. in the long run its replacing the DI resins that cost you the most money so get a good top quality RO membrane to start and also get a unit with a pressure gauge and tds meter.
 
All good advice above! As far as the pressure gauge and TDS meters go, you can add them later, but I recommend getting them from the start for the following reasons:

(1) They are cheaper as a package, and
(b) You don't get a chance to procrastinate.

Also, Air, Water and Ice make good units. When I received my unit, there was some shipping damage. AWI customer service took care of it very promptly.

$0.02
- ted
 
I just ordereed one on line, but I have the link at work. It was only $85.00 plus shipping from CA.
I'll get you the link tomorrow.
I saw it on nother thread on Reefcentral.
It's 125 gallon per day, plus DI, and a 3 stage filter.
Doug
 
<a href=showthread.php?s=&postid=11206594#post11206594 target=_blank>Originally posted</a> by scubadoo2
I just ordereed one on line, but I have the link at work. It was only $85.00 plus shipping from CA.
I'll get you the link tomorrow.
I saw it on nother thread on Reefcentral.
It's 125 gallon per day, plus DI, and a 3 stage filter.
Doug
Click to expand...

when you get it take a close up photo of the label or the membrane and post it
 
Here's the link to the unit I bought, and a picture of the RO membrane.
http://www.purewaterclub.com/catalog/product_info.php?cPath=28&products_id=41

showphoto.php
 
I got my RO/DI unit from The Filter Guys on here, and have been extremely satisfied. They have top notch customer service, and have no problems answering any questions and discussing option at length. Just a simple plug for a company that I have enjoyed doing business with. Sometimes the extra cost is worth the better service.
 
i asked someone else to stop in here. i dont know anything about that membrane but the DI part is not very good
 
I was asked to pop in here and comment on RO/DI units so pardon the intrusion.

Pure Water Club looks to me like someone on e-bay that went by millet or something similar. The units leave a lot to be desired at best.
First off no US manufacturer winds a 125 GPD RO membrane, not one. That right there should raise a red flag. Second notice thye do not tell you who the manufacturer is? I did a little poking aroundsome time ago and found the membranes at that time to be a Chinese knock off not even certified for sale in the US.

If we look a little closer you see a granular activated carbon cartridge before the membrane which is right next to worthless, its good for a maximum of 300 gallons of normally chlorinated water. It also produces carbon dust as it wears out and can contribute to membrane fouling.

Next it has a 1 micron carbon block. You are better off tossing both these carbons and get a single 0.6 or 0.5 Matrix Chlorine Guzzler carbon block good for up to 20,000 gallons.

Then the mysterious 125 GPD membrane.

Next they take a couple of 6 oz horizontal tubes and tout them to be efficient. They will never on their best day come close to a single standard 10" canister with a single refillable 20 oz cartridge. The verticals use a bottom up flow so all resin and water come into contact with each other and velocity really is not an issue, no need for a needle valve and drip,drip,drip.....

For the $85 you are basically getting some housings and little else of value. I don't see an RO bypass valve, a pressure gauge, a TDS meter....

For $161 Buckeye Field Supply, an RC sponsor gives you a true Dow Filmtec 75 GPD RO membrane, a Matrix carbon block, a true vertical DI, a much better prefilter, a handheld Hanna TDS meter, an inline pressure gauge, an adjustable flow restrictor if you request it and much more. Don't be fooled by the e-bay fly by nights that may not be here tomorrow. I along with others have e-mailed this vendor asking for info but never received a reply. That alone tells me something. Call one of the RC sponsors or get in touch with them through the sponsors forums and you normally have an answer in an hour or two tops.
 
hmmm... well as you can see youll get a ton of different answers to this question. All I can say is that I own the maximus RODI unit from aqua safe that I got off of Ebay. it cost me 89 for the complete system and at the time it came with a tds meter and a pressure gauge... I have been using the unit for over two years now with no problems... when my tds gets to 3 or 4 (like every year) I just change all of my filters, which I also ordered a case of at the time for ~90. So for ~180 I have had 2 years of water that has been fine on my tank(and I still have 1/2 a case of filters left)... If I needed to buy another system or parts to fix my system I would just go and buy another of theirs and be done with it...
BTW aquasafe has been in business for over two years now, so they are no fly by night...just my .02
Eric
 
Some info is not all that good though.
Consider, prefilters and carbons have very little to zero effect on final effluent TDS. Changing the filters annually or at 3-4 TDS is not wise at all. You change filters at 6 month intervals or if you have an inline pressure gauge, when you begin to see a pressure drop at the membrane. You cna also use a low range chlorine test kit to monitor carbon effectiveness but I would not recommend this to someone who only tests occasionally, it has to be done religously or you cna ruin a membrane in a hurry
You also should disinfect the housings at least annually if not every 6 months at filter changes, it takes a whole 10 minutes tops and could save your life.
Cheap filters do little to protect the membrane. Good filters can make a membrane last 10 years, ask Randy Holmes Farley. An $89 unit every two or three years is more expensive than a $160 unit every 7 to 10 years or more. Those who recommend the e-bay units have never experienced a good unit and have nothing to compare to or they would change their tune. I have compared side by side and can show you the differences, some are major.
 
Welll….

Desertrat may have a point about the RO membrane, but frankly in my book its only one part of the whole package. The unit I bought from Ebay contained these pieces: 1 sediment, 2 carbon chambers, Ro Membrane, di chamber, 3.2 gallon storage tank, TDS meter, pressure gauge, faucet attachment, tubing, and shut off valve. This cost me $89!
Buckeye charges about $242 for this system! (see the reef/residential system). So an $89 dollar unit every three years comes pretty close to a $242 system if you can get all the parts on that system to last 9yrs(which I doubt).

Last time I went to home depot I wanted to pick up another storage tank for extra volume- they cost about $50 there. For just a little more than that price I can just go and buy a brand spankin new system… *maybe* you can get a ro membrane to last a long time, but seals will fail in other areas, your shut off valve will fail, the diaphragm in your storage tank definitely wont last that long either.

Bottom line, you’ll pay for one thing or another. Just remember, the goal is to get to near 0 tds- it doesn’t matter if you pay 89 or 250… just depends on how you want to look at the whole package in my book. I used to buy more expensive stuff- computers, printers, etc… I find these days its cheaper, easier, and faster to just start fresh with disposable systems than to spend time and money trying to maintain and repair many things- you have to make the call on the time/money reward.

I would recommend changing filters every 6mo as well, but hey life happens…

Tank predator-Feel free to PM me if you need any more info.

Cheers,
Eric
 
That WOUND membrane threw me too. the DOW membranes look more like a rolled up mini corugated cardboard to me. made of porous plastic. so this unit if it does much at all, relies mostly on the DI resin to remove everything. which means you have a high particulate prefilter for the DI resin. and will have to replace the expensive resin very often, after few gallons. there are good units and bad units on ebay and elswhere. But a DOW membrane still seems to be the gold standard. and it is not a wound filter. its a membrane. particulate filters are wound.

but now i saw something on the science or discovery channel about a new RO filter material/configuration called Z-WEED? It may save us all. Some day......
 
All membrane manufacturers call it "winding" the membrane. Its a term they use since the membrane fabic and the seperator sheets are stacked and wound around a central core. Its not like winding string or yarn. The membrane is an extremely thin sheet of plastic film with a material almost like very fine window screen for a seperator.
 
thank you AZ for clarifying that. I was thinking ball of yarn. My cat must be rubbing off on me. I dont normally think of a permeable membrane as a winding. learn something new everyday.
 
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