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#1
01/09/2008, 11:59 AM
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RO/DI units?
Hi,
I'm new here so be gentle.  I have been looking for an RO/DI unit and am feeling overwhelmed with all of the choices. I've looked on Airwaterice, and drfostersmith, and others but don't know which are quality and which are overpriced. Also do I need 100gpd if I'm just using this for top off and water changes for a 10g system? Any insight would be great! |
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#5
01/09/2008, 01:36 PM
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From what I've been told you will not get 100 gallons a day unless you have really high water pressure or you get a booster pump. Another thing that affects them is water temperature.
Marc has them www.melevsreef.com His install pages are good too. |
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#6
01/09/2008, 03:50 PM
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check out purely h2o.com I have the optima vision 75 and could not be happier. I would suggest a 75gpd over the 100gpd because your rejection rate decreases from 98% down to about 92%. For your size tank 75 is plenty. Any of the RODI sponsors on here will set you up right.
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#7
01/09/2008, 04:22 PM
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When it comes down to it - many of the "core units are similar, if not the same." (so it seems)
What really matter is the TDS rejection rate and the type/brand of filters being used. I would not recommend a horizontal DI setup - DI sits on top of the main unit laying down. There are a few economical choices out there and are really great units! I just purchased the Ocean Wave+ from filterguyz and absolutely love it! Literally took me 10 minutes to start making RO/DI from the time I took it out of the box. Melev has a nice system he sells as well. Good luck!
__________________
Thank you. Drive Thru! |
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#8
01/09/2008, 04:25 PM
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My unit from the filter guys was on the wall and making water in under 10 mins also, easiest install ever!
Fun, Why do you not reccomend the DI unit on top? Last edited by dsn112; 01/09/2008 at 04:34 PM. |
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#9
01/09/2008, 09:03 PM
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True 10" canister and cartridge type DI filters are far superior due to better flow characteristics, bottom up flows, plus thye hold much more resin. Horizontal units can short circuit or channel so not all water comes into contact with the DI resin.
In general stay away from 100 GPD units especially if they have a Dow Filmtec membrane. The 100 GPD Dow is not a reverse osmosi membrane at all but is nano filter, the difference is 90% efficiency versus 98% efficiency. To get the rated GPD out of a Dow Filmtec 75 GPD RO membrane you need water pressure at 50 psi and water temperature of 77 degrees F. Lower temp and or pressure will produce less water. If its a GE Water membrane or Applied Membranes membrane than it takes 77 degrees still but 65 psi pressure to produce their rated flows. What that means is a 100 GPD GE or Applied membrane is about equal to a 75 GPD Dow Filmtec membrane. |
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#10
01/09/2008, 10:00 PM
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I recommend The Filter Guys as well. They are great about responding to any questions you have and make a good product that comes with simple instructions for installation.
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#11
01/09/2008, 10:13 PM
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Stick with a vendor that builds and sells water treatment devices as their primary business. Companies like Seachem, Kent and others leave a little to be desired.
Look at people like www.spetrapure.com www.melevsreef.com www.airwaterice.com www.buckeyefieldsupply.com www.thefilterguys.biz www.purelyh2o.com You can't go wrong with any of them as long as you stick with the true reef quality systems in the $150 and up price range. Look for features like a 75 GPD RO membrane, refillable vertical DI filter, Matrix carbon block, inline pressure gauge, handheld TDS meter, RO bypass valve etc. You should be able to find all of these for less than $200. |
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#14
01/10/2008, 09:05 PM
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Dow Filmtec is a brand of membrane. Most vendors use them in the 75 GPD version and they are the number one choice. Its the 100 GPD Dow membrane you want to stay away from not the 75. The 100 is NOT a RO membrane but is in fact a much less efficient nano filter. Nanofilters are not approved in the US by ANSI/NSF for drinking water since they do not reduce bacteria and viruses to what is considered as safe level for human consumption. Thye provide what is called 2 log removal where a RO membrane provides 3 log removal.
Dow Filmtec provides bulk membrane materials to other membrane winders like Applied who then wind or produce their own versions similar to Dows. Both Applied and GE Water sell what thye consider to be a 100 GPD RO membrane which is basically identical to a Dow Filmtec 75 GPD RO membrane. The difference is in they way the rate the GPD production. Both GE and Applied say it takes 65 psi and 77 degrees to produce 100 GPD. If you put that on a graph it shows they produce 75 GPD at 50 psi or 90 GPD at 60 psi. Now Dow Filmtec says their 75 GPD membrane gets its rating at 50 psi (see the similarity with the GE and Applied) and 77 degrees. Again if you graph the Dow it shows it produces 90 GPD at 60 psi and 100 GPD at 65 psi. Its all in how they juggle the numbers. Dows 100 GPD nanofilter puts out 100 GPD at 50 psi and more like 125 GPD at 65 but the kicker is it is only 90% efficient where their 75 GPD is 96-98% efficient. Don't even consider the 100 GPD Dow as it will eat your lunch in DI replacements. If you want the best RO membrane consider Spectrapures 90 GPD SpectraSelect series RO membrane. It is the only 100% individually hand tested and guaranteed 98+% rejection rate (efficient) RO membrane on the market. Spectrapure hand tests every one of them and then stores them wet in a special solution unlike anyone else. This process produces a very efficient membrane, mine is averaging 99.23% over an 18 month period and still going strong. You pay more initially but the savings in DI resin is amazing. Combine the Select membrane with Spectrapures proprietary hand blended DI resins like the MaxCap and SilicaBuster and you have a system that cannot be touched by anyone. Years of testing and research have paid of for them. |
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