Comprehensive RO/DI efficiency study, especially e-bay units.
- Thread starter aquaman67
- Start date
jdieck
New member
Two Filmtec nominal at 70 gpd high rejection membranes conected in series (water saver) combined capacity at 75 psi of 180 gpd
Inlet at 75 psi with TDS at 130, outlet from RO at 1 tds. 99.2% efficiency.
One membrane is 6 years old and the other 4 years old.
Using the HM DM-1 Dual TDS Meter.
Make 75 gallons per week. Membranes are backflushed for 2 minutes after each use.
Inlet at 75 psi with TDS at 130, outlet from RO at 1 tds. 99.2% efficiency.
One membrane is 6 years old and the other 4 years old.
Using the HM DM-1 Dual TDS Meter.
Make 75 gallons per week. Membranes are backflushed for 2 minutes after each use.
NaClH20reeffish
New member
Did you want to tell everyone how you had to fix your ebay unit? Just so they can do the same?
abulgin
Premium Member
Thank you for this. I meant to post a picture of my unit so everyone can see this very easy, and very important, modification. I will do so when I get home tonight. It's important to note that I didn't "fix" my unit--I simply reconfigured the position of my DI units.
Aquaman, maybe when the dust settles from this thread, you or someone would volunteer to put together a spreadsheet showing results. That would be pretty helpful. Also, you didn't ask for it, but I'm now thinking that it may be useful to know which RO membranes everyone is using. I think for purposes of this thread, it is important that we know whether the filters are the "stock" filters that came with/come with the unit, or whether anyone upgraded to a better filter.
from the looks of this thread, there are no "better filters"
we are all within like 2%... everyones RO is getting their output under 5TDS save for the 1 guy up there with low water pressure.
the thread appears to basicly say they are all equal as far as how long your DI will last. it doesnt say how long your RO will last though, which I thought was the real question... I cant imagine anyone actually records total volume of water that they make.
we are all within like 2%... everyones RO is getting their output under 5TDS save for the 1 guy up there with low water pressure.
the thread appears to basicly say they are all equal as far as how long your DI will last. it doesnt say how long your RO will last though, which I thought was the real question... I cant imagine anyone actually records total volume of water that they make.
aquaman67
Active member
The point I'm really trying to make is consistency.
Here's a purewaterclub unit on ebay.
http://cgi.ebay.com/New-Reef-6st-10...ryZ20684QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
From their own web page:
Water Purity Reference: (1.)Tap or well water(300 PPM), (2.)After RO system(20 PPM)
So that's 93% efficiency. They don't tell you that and unless you do the math you'd never know. They don't just come out and say it's only 93 % efficient. And that's what I don't like about ebay. You have to know what you're looking at or get lucky. The 75 GPD units seem to work better than the 100 GPD units.
Here's a purewaterclub unit on ebay.
http://cgi.ebay.com/New-Reef-6st-10...ryZ20684QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
From their own web page:
Water Purity Reference: (1.)Tap or well water(300 PPM), (2.)After RO system(20 PPM)
So that's 93% efficiency. They don't tell you that and unless you do the math you'd never know. They don't just come out and say it's only 93 % efficient. And that's what I don't like about ebay. You have to know what you're looking at or get lucky. The 75 GPD units seem to work better than the 100 GPD units.
AZDesertRat
In Memoriam
This thread is somewhat pointless as it takes months to years to see the effects of cheap prefilters and carbons on the life of an RO membrane. In my case at 835 TDS tap water the effects can be seen in weeks or a few months at most. With a TDS of 100 it would not be so obvious but the effects are still there. The point is using better quality filters will improve the lifespan and longterm performance of a membrane and this is proven time and again. I look at a RO/DI system as a "tool" and I take care of my tools. I fully expect to have the same unit with the same membrane around for years and years, so I use only high quality replacements.
If I figure cost of ownership over a 6-10 year period I am money ahead by doing so. In a normal system you can expect a maximum lifespan of a membrane to be 3 years. With my old system I averaged 18 to 24 months per RO membrane. I expect to see 9-10 years on mine now. Randy Holmes Farley just reported 10 years on his original Spectrapure RO membrane.
With a 96-98% rejection rate RO membrane I can expect to see about 150 gallons per 20 oz refill of good quality mixed bed DI resin based on my personal testing and what I hear from my fellow reefers in the Phoenix area. By using the good filters and the Select membrane I am averaging well over 800 gallons per DI cartridge using Spectrapures resins.
Using those numbers I figure I will save the cost of 3-5 replacement RO membranes and 50 to 100 DI cartridges in a 6 to 10 year period based on 150-200 gallons of DI per month.
Yes my prefilters, carbon blocks and DI cartridges cost more to replace but if I am saving that many replacements I am still way ahead in both dollars and labor expended. Its a win win situation for me!
If I figure cost of ownership over a 6-10 year period I am money ahead by doing so. In a normal system you can expect a maximum lifespan of a membrane to be 3 years. With my old system I averaged 18 to 24 months per RO membrane. I expect to see 9-10 years on mine now. Randy Holmes Farley just reported 10 years on his original Spectrapure RO membrane.
With a 96-98% rejection rate RO membrane I can expect to see about 150 gallons per 20 oz refill of good quality mixed bed DI resin based on my personal testing and what I hear from my fellow reefers in the Phoenix area. By using the good filters and the Select membrane I am averaging well over 800 gallons per DI cartridge using Spectrapures resins.
Using those numbers I figure I will save the cost of 3-5 replacement RO membranes and 50 to 100 DI cartridges in a 6 to 10 year period based on 150-200 gallons of DI per month.
Yes my prefilters, carbon blocks and DI cartridges cost more to replace but if I am saving that many replacements I am still way ahead in both dollars and labor expended. Its a win win situation for me!
aquaman67
Active member
Right,
To me it's mis-leading to say the least.
I guess I'm not being clear. There is a difference in what you can get, membrane wise. I'm sure there are people who have the less efficient membanes who haven't or won't post their results here. That's how the thread I mentioned in the archives from a few years ago got started in the first place. People were complaining about burning through DI resin. After I saw their site and did the math I figured out what was going on. After that people asked for true RO membranes. I didn't find filter direct on ebay. Maybe they stopped selling on ebay?
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AZDesertRat
In Memoriam
Honest vendors use the published figures provided by the membrane manufacturer and do not make up facts and figures out of thin air.
I see two red flags here.
One is they are being deceptive and contradictory as to the performance and are afraid to publish real factual numbers and two is they are using no name products otherwise they would be proud to publish who makes their components and how well they work. Dow, GE and Applied have tested their membranes for years and have volumes of published data that is available to their resellers for promotional materials. No need to make numbers up.
If you were selling a product which was made up of name brand internationally famous parts and pieces wouldn't you state those names in your advertising to draw in customers??? Most of us are very observant and are looking for the best product at the best price. If I can sell you a XYZ RO/DI using the same components as Joe Schmoe but at a significant cost savings don't you think I am going to promote my product accurately?
What seems to be overlooked is quality costs money. Even in huge volumes a Dow membrane or Matrixx+1 carbon block is going to cost more than an untested and uncertified imported product. Companies pay large sums of money to get a product ANSI/NSF certified and it has to be passed on to the consumer. This certficiation is for our protection and is important. Its just not possible to construct a RO/DI unit using quality components and sell it for $89 when a membrane alone costs $30 at wholesale even by the truck load. Add in quality prefilters. carbon blocks, housings, cartridges, DI resin, valves, fittings and gauges and it all adds up.
I see two red flags here.
One is they are being deceptive and contradictory as to the performance and are afraid to publish real factual numbers and two is they are using no name products otherwise they would be proud to publish who makes their components and how well they work. Dow, GE and Applied have tested their membranes for years and have volumes of published data that is available to their resellers for promotional materials. No need to make numbers up.
If you were selling a product which was made up of name brand internationally famous parts and pieces wouldn't you state those names in your advertising to draw in customers??? Most of us are very observant and are looking for the best product at the best price. If I can sell you a XYZ RO/DI using the same components as Joe Schmoe but at a significant cost savings don't you think I am going to promote my product accurately?
What seems to be overlooked is quality costs money. Even in huge volumes a Dow membrane or Matrixx+1 carbon block is going to cost more than an untested and uncertified imported product. Companies pay large sums of money to get a product ANSI/NSF certified and it has to be passed on to the consumer. This certficiation is for our protection and is important. Its just not possible to construct a RO/DI unit using quality components and sell it for $89 when a membrane alone costs $30 at wholesale even by the truck load. Add in quality prefilters. carbon blocks, housings, cartridges, DI resin, valves, fittings and gauges and it all adds up.
bubble girl
New member
I got a RO/Di from ebay-filterdirect, It was a 100 GPD model. My tap water TDS is about 200. After Ro only it was 20 TDS. It’s about a year old. 90 % efficient by aquaman’s calculation formual. I am going through Di media faster than I think I should so I’m going to buy a new unit as soon as I can. I hate those little Di canisters anyway. It won’t be from ebay but from a sponsor of R/C. I’ve learned so much from here. Thank you aquaman and AZDesertRat.
AZDesertRat
In Memoriam
I believe you said Ultratec or something and the part number did not match up with a Dow Filmtec product if I remember correctly.
Ultratec is in fact a legitimate California company but I cannot find any mention of NSF certifications or testing on their membranes.
Pirates and knock offs take advantage of trade names by making items appear similar and names sound close to the same. This is another misleading technique they use. Change things just enough so you don't get sued, not that they can stop a pirate in China anyway.
Ultratec is in fact a legitimate California company but I cannot find any mention of NSF certifications or testing on their membranes.
Pirates and knock offs take advantage of trade names by making items appear similar and names sound close to the same. This is another misleading technique they use. Change things just enough so you don't get sued, not that they can stop a pirate in China anyway.
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RichConley
New member
Bought my ebay unit in 2003. Still kicking with the original membrane, still 98%+.
RichConley
New member
All you need to do is replace the DI cannister and the membrane. $30 for a filmtech 75gpd (from any number of sponsers) and another $30 or so for the DI 10" cannister and refillable cartridge. Theres no reason to replace everything. 10" Cannisters are 10" cannisters.
yeah, that sounds right, the ultratec part. when I typed in the part number I found an ultratec spreadsheet though, which "equated" their filters to the other guys, like this is our equivalent of that, not that I put a lot of faith in a companies datasheets, tend to be biased.
the filter number that didnt match up was the BFS RO filter number, was not on filmtec's listing, I later realized this was because BFS was not showing the real part number either. they used a BFS part number. I think it was safe to presume it was he 75gpd membrane that ultratec had matched to it, it was the only 75gpd drinking water membrane as far as I could see from filmtec.
AZDesertRat
In Memoriam
Dow Filmtec membranes are usually a TW-1812-XX with the XX being 50, 75 etc. Some units use a less common TW-1810 series which is not interchangable, these include Whirlpool, Lowes, Sears and some Watts Premier products.
Companies which carry a NSF certification provide very accurate data as it is a very important part of that testing and certification process. This process can take several months to a couple years to complete, is very rigorous and very expensive. Both Dow and GE/Desal have good charts showing removal efficiencies of various solutes and the effects of temperature and pressure on a membrane. Good info for sure.
Companies which carry a NSF certification provide very accurate data as it is a very important part of that testing and certification process. This process can take several months to a couple years to complete, is very rigorous and very expensive. Both Dow and GE/Desal have good charts showing removal efficiencies of various solutes and the effects of temperature and pressure on a membrane. Good info for sure.
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