Comprehensive RO/DI efficiency study, especially e-bay units.
- Thread starter aquaman67
- Start date
Water temperature, line pressure, and what's in the water impact RO efficiency, so even if folks had perfect TDS measurements, I think making comparisons between different users is going to be tricky to interpret in a thread like this.
aquaman67
Active member
True...this is hardly scientific.
This page
http://www.aquacave.com/dow-100-gpd-reverse-brosmosis-membrane-1822.html
List TF-1812-100 as a DOW filmtec membrane.
Makes you wonder....
AZDesertRat
In Memoriam
100 GPD membranes are not always less efficient but that is the case with the Dow Filmtec TW-1812-100. In the case of Ultatecs TF-1812-100 it should really be compared to Dow Filmtecs TW-1812-75 not the 100. Ultratec claims 100 GPD at 60 psi and 77 degrees which is similar to Dows 75 GPD membrane when you increase the pressure from their figure of 50 psi up to 60 psi. The rejection rate should be 96-98% not 90% but I could not find the data on their website to back that up.
AquaCave is Aqua FX and looking further at their various sites and pages I see different conflicting information like Ultratec part numbers coupled with pictures of Dow membranes and other things like Aqua Engineering brand "made with genuine Dow materials" etc.
AquaCave is Aqua FX and looking further at their various sites and pages I see different conflicting information like Ultratec part numbers coupled with pictures of Dow membranes and other things like Aqua Engineering brand "made with genuine Dow materials" etc.
interesting, but yeah, it isnt. thats not what ours look like anyway. the label I mean. and we know dow doesn label like that either.
Id say its shady, but that depends what that site actually sent you... 49.95 isnt a great price for either one though, so kind of a mute point.
Id say its shady, but that depends what that site actually sent you... 49.95 isnt a great price for either one though, so kind of a mute point.
AZDesertRat
In Memoriam
Fill your DI cartridges completely full and they will work much better. Fill them, tap them on the table top, fill again, tap again and do a final fill before replacing the sponge and that way the water has longer contact with resin. Guaranteed to function better and longer.
carlso63
Reefkeeping since 1977
I look back a day later, and now I can see the real purpose of this "Comprehensive Efficiency Study" is yet another thinly disguised "bash" thread...here we go again 
I, for one really don't give a rat's buttocks what the wording on some advertisement says; I care how the thing performs...
I get a 98+% rate on my eBay unit - that is my real world experience. I could care less if some idiot ad writer figured it out to be 90% or 93% or whatever; and, most importantly, that rate is DAMN CLOSE to the rate of the more expensive units - so stop arguing that you half a percent higher rate is sooo soooooo much "better" - because it ISN'T... and the amount of "longer life" you get out of your DI resin isn't significant, cost-wise... unless you are are AZRat who has up to 1300 ppm most days where a half percentage point might be 7 - 10 ppm difference after RO - for basically everyone else a half percentage point higher rate equates to less than 1 ppm difference post RO so you will use up your DI resin at almost the exact same rate that I will...
My unit takes my 220ppm tap down to 4ppm after RO and the DI brings it to 0. And YES, I reoriented my DI cartridges, too... funny how that is considered "having to fix it to get it to work" here and not "modding" for better performance like any one of the hundred some-odd other "fixes" we as hobbyists do all the time to our skimmers, or powerheads, or light fixtures and yes, our water purification units -
And despite all the hype about filters, the TRUTH is that just about ALL of us - with the possible exception of AZDesertRat - all of us will end up changing our filters as part of "routine maintenance" (like once a year or once every 6 months, for example) and NOT because "...the cheap filters don't last as long as the expensive ones"... I change my prefilters once yearly; if I decided to "upgrade" to the "premium quality" brand filters I WOULD STILL CHANGE THEM ONCE A YEAR. No Difference.
And, when the dust settles, the 0 ppm I am getting out of my unit is the SAME as the 0 ppm you are getting out of your unit - no matter what psuedo scientific terminolgy you pull out of your whazoo - ZERO TDS IS ZERO TDS. PERIOD
And the main driver behind unit choice should be the incoming (tap) TDS level of the user. There is no need whatsoever for someone who is getting 50, 100, even 200 ppm out of their tap to feel they HAVE to have a premium unit in order to have "safe" water for their Reef... that is just baloney. Of course, if they CHOOSE to own the best unit money can buy, that's their right and that's fine - but they don't NEED to. And they should stop inferring that everyone else "needs to" as well...
Conversely, someone like AZDesertRat DOES NEED TO use a premium unit. My ebay job wouldn't last a week with his 800-1300ppm tap water. So he, in effect, actually has less of a choice because of his harsh water supply.
And this glorified peeing contest over which choice is "better" really doesn't change the facts one bit...
So, are we done with this yet?
I, for one really don't give a rat's buttocks what the wording on some advertisement says; I care how the thing performs...
I get a 98+% rate on my eBay unit - that is my real world experience. I could care less if some idiot ad writer figured it out to be 90% or 93% or whatever; and, most importantly, that rate is DAMN CLOSE to the rate of the more expensive units - so stop arguing that you half a percent higher rate is sooo soooooo much "better" - because it ISN'T... and the amount of "longer life" you get out of your DI resin isn't significant, cost-wise... unless you are are AZRat who has up to 1300 ppm most days where a half percentage point might be 7 - 10 ppm difference after RO - for basically everyone else a half percentage point higher rate equates to less than 1 ppm difference post RO so you will use up your DI resin at almost the exact same rate that I will...
My unit takes my 220ppm tap down to 4ppm after RO and the DI brings it to 0. And YES, I reoriented my DI cartridges, too... funny how that is considered "having to fix it to get it to work" here and not "modding" for better performance like any one of the hundred some-odd other "fixes" we as hobbyists do all the time to our skimmers, or powerheads, or light fixtures and yes, our water purification units -
And despite all the hype about filters, the TRUTH is that just about ALL of us - with the possible exception of AZDesertRat - all of us will end up changing our filters as part of "routine maintenance" (like once a year or once every 6 months, for example) and NOT because "...the cheap filters don't last as long as the expensive ones"... I change my prefilters once yearly; if I decided to "upgrade" to the "premium quality" brand filters I WOULD STILL CHANGE THEM ONCE A YEAR. No Difference.
And, when the dust settles, the 0 ppm I am getting out of my unit is the SAME as the 0 ppm you are getting out of your unit - no matter what psuedo scientific terminolgy you pull out of your whazoo - ZERO TDS IS ZERO TDS. PERIOD
And the main driver behind unit choice should be the incoming (tap) TDS level of the user. There is no need whatsoever for someone who is getting 50, 100, even 200 ppm out of their tap to feel they HAVE to have a premium unit in order to have "safe" water for their Reef... that is just baloney. Of course, if they CHOOSE to own the best unit money can buy, that's their right and that's fine - but they don't NEED to. And they should stop inferring that everyone else "needs to" as well...
Conversely, someone like AZDesertRat DOES NEED TO use a premium unit. My ebay job wouldn't last a week with his 800-1300ppm tap water. So he, in effect, actually has less of a choice because of his harsh water supply.
And this glorified peeing contest over which choice is "better" really doesn't change the facts one bit...
So, are we done with this yet?
Carlos- I didnt see anywhere AZdesertrat made any claim of bashing. I think the point the original poster was looking to gain was in general consistientcy . It could actually be beneficial if enough posters responded.Especially if those from the same area (same water supply)using different units were seeing different results.Lets give it a chance.
Maybe we could include pressure and temp for those that are able. I will post mine as soon as I get a chance.
-Graves
Maybe we could include pressure and temp for those that are able. I will post mine as soon as I get a chance.
-Graves
aquaman67
Active member
Sheesh, calm down.
FYI, my frame of reference is from about 2 years ago. I’ve been out of the loop thanks to an all expenses paid vacation to the Middle East courtesy of the US Army.
It does seem that the quality of membranes being sold on ebay has increased greatly. That was the point of this thread. To see exactly what’s out there. I didn’t have an ulterior motive for posting this. I had no way of knowing how the results would turn out. I really want to know and more importantly others to know what is out there. I already have an RO/DI and I’m not in the market for one either. I admit I did have a feeling that people were still being taken advantage of. That doesn’t seem to be the case anymore. Think what you want. I know what was being sold 2 years ago was junk and I wanted to see if anything has changed. It has. I said it, it has! Things are better for consumers. Retailers stopped selling those inefficient membranes and people are not being taken advantage of …well, almost.
I still feel that by not posting the efficiencies of the membranes and by just saying “tap water at 300 TDS in â€"œ 20 TDS out of the membrane†is very misleading. Why make people do the math? How many people would even know how to calculate efficiency based on the numbers they give? Why not just say it? Those inferior membranes ARE still being sold, I was able to find one. Why be shady? What are they hiding? I absolutely hate being taken advantage of. And that’s why I rail against people who are, IMO, being deceptive. Just come out and say it. “This membrane is 95 % efficient.†That’s all I’m asking! I’m not knocking the people who knowingly buy them, I’m knocking the people who sell them to other people who have no idea what they’re getting and try to make it look like you are really getting a GE membrane when you’re NOT! That’s all. I can’t make this any clearer. Think what you want of me. I really don’t care. As long as one person makes a decision based on facts and doesn’t get tricked, then I’m happy. If they get an ebay RO/DI and it works for them, that’s fine with me. So you have to flip the DI canisters vertical so they don’t channel, that’s fine too. But before a few of us mentioned that, no one knew! And the GAC pre-filters. Many people didn’t know they were inferior too, so they bought them. Now some people know. That’s the point….to get information. That’s the whole point of Reef Central, to get information from others. AZDesertRat has worked in the water industry for 30 years. I’ve been working in it for 10 years. We tell you there is a difference in what is being sold as RO membranes. Do you think we are making all this it up?
It’s not some voo doo or pseudo science and it doesn’t come from my wazoo. It comes from book written by the American Water Works Association. Nano membranes don’t remove as much as “true RO†membranes. You can choose to believe it or not. They look the same, but they don’t perform the same. And here’s the important part…they are being represented, IMO, as “just as goodâ€Â. And that’s just wrong to me. And that’s my point. Yes, you can get a good RO/DI on ebay. You really can. I don’t think I’ve ever told anyone not to buy one. But I do want everyone to know exactly what they are buying. That’s all. So it seems they have stopped selling those crappy 100 GPD membranes. Great. The seller that was very guilty of it doesn’t appear to even sell on ebay anymore and I’m glad.
I have nothing against someone who KNOWINGLY purchases what ever they feel suits their needs. I buy shoes at WalMart. My kids laugh at me, but they are half the price and generally last just as long. You do get the occasional pair that falls apart the first time they get wet, but over all there is nothing wrong with shoes from WalMart. We all don’t need Air Jordans. I got it.
People please, just make informed decisions! That’s all. Know that there are people out there willing to sell you something that looks like a duck but doesn’t walk or quack like a duck…
Peace out….
FYI, my frame of reference is from about 2 years ago. I’ve been out of the loop thanks to an all expenses paid vacation to the Middle East courtesy of the US Army.
It does seem that the quality of membranes being sold on ebay has increased greatly. That was the point of this thread. To see exactly what’s out there. I didn’t have an ulterior motive for posting this. I had no way of knowing how the results would turn out. I really want to know and more importantly others to know what is out there. I already have an RO/DI and I’m not in the market for one either. I admit I did have a feeling that people were still being taken advantage of. That doesn’t seem to be the case anymore. Think what you want. I know what was being sold 2 years ago was junk and I wanted to see if anything has changed. It has. I said it, it has! Things are better for consumers. Retailers stopped selling those inefficient membranes and people are not being taken advantage of …well, almost.
I still feel that by not posting the efficiencies of the membranes and by just saying “tap water at 300 TDS in â€"œ 20 TDS out of the membrane†is very misleading. Why make people do the math? How many people would even know how to calculate efficiency based on the numbers they give? Why not just say it? Those inferior membranes ARE still being sold, I was able to find one. Why be shady? What are they hiding? I absolutely hate being taken advantage of. And that’s why I rail against people who are, IMO, being deceptive. Just come out and say it. “This membrane is 95 % efficient.†That’s all I’m asking! I’m not knocking the people who knowingly buy them, I’m knocking the people who sell them to other people who have no idea what they’re getting and try to make it look like you are really getting a GE membrane when you’re NOT! That’s all. I can’t make this any clearer. Think what you want of me. I really don’t care. As long as one person makes a decision based on facts and doesn’t get tricked, then I’m happy. If they get an ebay RO/DI and it works for them, that’s fine with me. So you have to flip the DI canisters vertical so they don’t channel, that’s fine too. But before a few of us mentioned that, no one knew! And the GAC pre-filters. Many people didn’t know they were inferior too, so they bought them. Now some people know. That’s the point….to get information. That’s the whole point of Reef Central, to get information from others. AZDesertRat has worked in the water industry for 30 years. I’ve been working in it for 10 years. We tell you there is a difference in what is being sold as RO membranes. Do you think we are making all this it up?
It’s not some voo doo or pseudo science and it doesn’t come from my wazoo. It comes from book written by the American Water Works Association. Nano membranes don’t remove as much as “true RO†membranes. You can choose to believe it or not. They look the same, but they don’t perform the same. And here’s the important part…they are being represented, IMO, as “just as goodâ€Â. And that’s just wrong to me. And that’s my point. Yes, you can get a good RO/DI on ebay. You really can. I don’t think I’ve ever told anyone not to buy one. But I do want everyone to know exactly what they are buying. That’s all. So it seems they have stopped selling those crappy 100 GPD membranes. Great. The seller that was very guilty of it doesn’t appear to even sell on ebay anymore and I’m glad.
I have nothing against someone who KNOWINGLY purchases what ever they feel suits their needs. I buy shoes at WalMart. My kids laugh at me, but they are half the price and generally last just as long. You do get the occasional pair that falls apart the first time they get wet, but over all there is nothing wrong with shoes from WalMart. We all don’t need Air Jordans. I got it.
People please, just make informed decisions! That’s all. Know that there are people out there willing to sell you something that looks like a duck but doesn’t walk or quack like a duck…
Peace out….
abulgin
Premium Member
I agree that it will be very insightful to see what's available, and for how much, but let's all be honest . . .
http://reefcentral.com/forums/showthread.php?s=&threadid=1429988&perpage=25&pagenumber=3
aquaman67
OIF 06-08 Vet
Registered: Feb 2002
Location: Tennessee
Occupation: Wondering why
Posts: 6691
quote:
--------------------------------------------------------------------------------
Originally posted by abulgin
My cheap RO membrane is 97.44% efficient.
--------------------------------------------------------------------------------
Congratulations!
You are one of the few people who got lucky!
07/14/2008 01:35 PM
abulgin
Premium Member
Registered: Jul 2007
Location: Baltimore, MD
Occupation:
Posts: 1117
quote:
--------------------------------------------------------------------------------
Originally posted by aquaman67
Congratulations!
You are one of the few people who got lucky!
--------------------------------------------------------------------------------
And you know this because you've conducted a study on all the people who have purchased a cheap eBay unit.
07/14/2008 01:49 PM
aquaman67
OIF 06-08 Vet
Registered: Feb 2002
Location: Tennessee
Occupation: Wondering why
Posts: 6691
quote:
--------------------------------------------------------------------------------
Originally posted by abulgin
And you know this because you've conducted a study on all the people who have purchased a cheap eBay unit.
--------------------------------------------------------------------------------
Go here.
http://archive.reefcentral.com/
Search for my user name. We did a thread about 2005 or 2006 where people posted their RO membrane efficiencies.
We can always start a new one if you like...
__________________
So, the point of this thread is to determine if, in fact, the RO/DI units being sold on eBay tend to be less effective/efficient than the more expensive models.
The results will be helpful for anyone looking to buy a unit.
abulgin
Premium Member
Well, I don't know how they can claim the 98-99% rate but state that the membrane takes 300 TDS water down to 20 TDS. That clearly is not 98-99%.
In this guy's defense (or not), his grasp of the English language is not great. The instructions for my unit were not written well, had gaps, and were hard to understand. Luckily, the thing came assembled so it was just a matter of figuring out which tubes went where.
"And, when the dust settles, the 0 ppm I am getting out of my unit is the SAME as the 0 ppm you are getting out of your unit - no matter what psuedo scientific terminolgy you pull out of your whazoo - ZERO TDS IS ZERO TDS. PERIOD"
Is this true? With an accuracy of 2% of full scale deflection (FSD) for a typical TDS meter, and a FSD of 1999 ppm, your "zero" might be 39ppm. Even with a FSD of 999, your TDS could be 19ppm. How many people calibrate their TDS meters? (Their efficiciency should stay the same of course)
Roy
Is this true? With an accuracy of 2% of full scale deflection (FSD) for a typical TDS meter, and a FSD of 1999 ppm, your "zero" might be 39ppm. Even with a FSD of 999, your TDS could be 19ppm. How many people calibrate their TDS meters? (Their efficiciency should stay the same of course)
Roy
AZDesertRat
In Memoriam
The average tap water TDS nationwide is about 250ppm. This number is rising all the time partly due to groundwater recharge from wastewater treatment plants runoff from storms and from lakes, rivers and impoundments concentrating the wastes. When rivers wer not damed and flowed freely this was not so much of an issue. Of course none of us were around then either!
A 1% or 2% increase or decrease in membrane efficiency can have a very big effect on DI lifespan and overall water quality. Remember that for every 2% you increase the membranes efficiency you DOUBLE the life of your DI resin/cartridge. That applies to everyone no matter how good or bad yor tap water is or how efficient your DI filter is or how much resin it holds.
A 1% or 2% increase or decrease in membrane efficiency can have a very big effect on DI lifespan and overall water quality. Remember that for every 2% you increase the membranes efficiency you DOUBLE the life of your DI resin/cartridge. That applies to everyone no matter how good or bad yor tap water is or how efficient your DI filter is or how much resin it holds.
Say you have 100ppm and your membrane removes 96%; this leaves you with 4ppm. If you go to 98% which is a 2% increase, you end up with 2ppm. Your DI resin should last twice as long filtering 2ppm as it would 4ppm.
Now, say you have 100pm and you remove 90%; this leaves you with 10ppm. If you increase RI efficiency by 2% to 92%, you end up with 8ppm. Wouldn't you obtain a 20% increase in DI lifespan rather than doubling the lifespan?
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