# R.O. unit recommendation



## paulie1972 (May 11, 2006)

I am looking to purchase a RO unit for my fish tanks and was wondering: what people here have experienced and what should I avoid? My water is VERY hard and has alot of dissolved solids in it. Should I get a de-ionizer stage for it? What are the benefits of a de-ionizer? What would be the most ideal package? Are there any brands that people would recommend? I have 6 tanks ranging in size from 30 gallons up to 90. Any suggestions from people with RO ubnits would be great. Thanks.


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## Brilliant (Jun 25, 2006)

I would avoid expensive name brand units that cost more.

I would suggest getting a 100GPD unit.

Deionizing resin provides that extra kick and reduces water to 0ppm TDS where as a good RO unit will produce about 20ppm water. For the planted tank I do not think the DI stage is as needed. I like the DI stage and continue to use this because I desire soft tank water and fertilizers make my water harder to the softer I can get...the better...IMO.

If you decide to go RO/DI
I would suggest getting a unit with twin sequencial DI resin catridges, this way the water is less likely to "channel" through the DI resin.

Here is a pic of my unit. If you have any further questions please dont hesitate to ask or PM me.


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## gnatster (Mar 6, 2004)

I have had great success with units from AirWaterIce.com pricing is competitive. Service is great.

I would not go for a 100gpd unit but a 75gpd. The membrane is the same but a 100gpd allows more "stuff" to pass through then a 75gpd. As mentioned above a DI unit is not really needed for plants. If you do want to go DI and cost is not the # consideration I would recommend that you get the full size canisters for DI and not the smaller cartridges. Futhermore I keep the CATI and ANI resins separate as they do not get exhausted at the same rate.

I can't speak highly enough of AirWaterIce.com Take a look at the TyphoonIII. You can always call and them and discuss your exact needs as well and they will create a unit for you.


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## werner (Jul 6, 2006)

You can try eBay- some sellers have aquarium-specific RO setups. You can get a complete RO/DI unit for under $100.


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## Brilliant (Jun 25, 2006)

I dont know about this claim. My unit is 100GPD and produces 0ppm water with the DI resin. Reverse osmosis is reverse osmosis.. I think the surface area is increased with the higher rated membranes. But then again I am just taking a stab in the dark here...if that were true the much larger units would seem worthless.

ebay is a great suggestion.


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## diablocanine (Jul 25, 2004)

Does this help? I do 200 gallons of water changes per week with it....DC
http://www.fellowshipofthefish.com/forum/viewtopic.php?t=37&sid=63f6ee8763aba489fff0098137da6345


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## gnatster (Mar 6, 2004)

Brilliant said:


> I dont know about this claim. My unit is 100GPD and produces 0ppm water with the DI resin. Reverse osmosis is reverse osmosis.. I think the surface area is increased with the higher rated membranes. But then again I am just taking a stab in the dark here...if that were true the much larger units would seem worthless.
> 
> ebay is a great suggestion.


The most commonly used membranes are the Filmtec models made by Dow. These are found in the vast majority of Ebay units as well as the private label ones from Kent and other "High end" RO units.

75 gpd part # FILMTEC TW30-1812-75 
100 gpd part # FILMTEC TW30-1812-100

The 75 gpd membrane has a 98% rejection rate while the 100 gpd membrane has a 90% rejection rate.

Sources

Dow/Filmtec Data Sheet on 24-36-50-75gpd membranes http://www.dow.com/PublishedLiterat...seps/pdfs/noreg/609-09010.pdf&fromPage=GetDoc

Dow/Filmtec Data Sheet on 100 gpd membranes http://www.dow.com/PublishedLiterat...seps/pdfs/noreg/609-00382.pdf&fromPage=GetDoc

Another factor to keep in mind is the Dow/Filmtec membranes are rated at nominal household water pressure of 50psi for standard city sourced water. Most every other membrane on the market, expecially the low cost Ebay models, is rated at 60psi. Running a lower psi then the membrane is rated at will significantly reduce production effluent. Membranes are also rated at a certain temperature. Running the membrane with colder water will reduce product. Conversely running at a higher temperature will increase product to a point. One risks destroying the membrane at to high a temperature.

I have done quite a bit of research on RO units before I purchased mine. I do not endorse a product or vendor unless I have significant experience with them. My recommendations do not come lightly. While you can save a few $ with an Ebay R.O. kep in mind you get what you pay for both in product quality and service before and after the sale.

The sting of low quality lasts longer then the joy of low price.


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## Laith (Sep 4, 2004)

gnatster said:


> ...
> 
> The sting of low quality lasts longer then the joy of low price.


Very well said!


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## wiste (Feb 10, 2006)

I agree that not all RO water is created equal.
My understanding is that water with this purity (98%) would be strictly dedicated for use in the aquarium.
That is, it is not for human consumption. 
Also, if the intention for end use is to use RO water mixed with tap water then this seems to be overkill.
Is there a noticeable benefit when using very pure water?


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## Brilliant (Jun 25, 2006)

gnatster said:


> The most commonly used membranes are the Filmtec models made by Dow. These are found in the vast majority of Ebay units as well as the private label ones from Kent and other "High end" RO units.
> 
> 75 gpd part # FILMTEC TW30-1812-75
> 100 gpd part # FILMTEC TW30-1812-100
> ...


OK great thanks for making that clear. I smelled BS but its apparent by those rejection rates that I am wrong. I still get 0ppm water with DI and 90% rejection rate. The carbon and DI resin are doing their jobs.

I purchased my unit 6 months ago. I could have purchased 3 of them at the "high end" pricing. I was also supported by the company afterwards when I had an issue...I moved away from the auto-shut-off valve and went with a timer and solenoid. Since ive only owned it 6 months I felt suggesting the same product I owned was a bit premature so I didnt, I understand what you mean.

I did a little bit of reasearch before purchasing and found out the same thing you mentioned....the majority of the units use the same parts, so I saved money and I went with ebay. Some things I dont skimp on like quality light fixtures and canister filters...so I understand you.

I still went with ebay and saved money on Eheim and my newest light fixture...there are risks.

About that temperature thing...at one point I was going to try running a coil of tubing submerged in hot water to feed the unit. I was hoping this would take the edge off my cool tap water in the winter.

My use of RO is for my fish....not really plants. It helps me keep solid water parameters and maintain low TDS after fertilizing.


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## Raul-7 (Feb 4, 2004)

You might want to consider a DI unit instead, it's purer than RO and better in a number of aspects. Firstly and most importantly, a DI unit produces no waste water at all. Another benefit is that you don't have to wait for hours until you can finally use pure water (DI units are rated in gp/minute as opposed to gp/day with RO). In addition, you don't need to bother with getting automatic float valves, large trash bins, etc just hook up a long hose from the output to your aquarium and you're set. Overall, it's much cheaper a to run if you factor in water bills, membrane replacements and all the other cartridges you have to replace over time. The only problem is that it won't produce as much an RO unit, but it can always be recharged fairly easily with NaOH and HCl - that's if you're willing to do so. 

The only DI unit I'm aware of is the Kent Deion 200-R (make sure you get the R - stands for rechargeable resins). Mine works perfectly so far.


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## gnatster (Mar 6, 2004)

Stand Alone DI Filters vs. RO/DI

Stand alone de-ionization filters are available, and DI water is more pure than RO water, but in most cases they are not worth the expense in the long run. The large capacity models have resins that can be reused, but this requires the handling of dangerous chemical solutions. Also, they are only capable of producing small quantities of water before the filter cartridges are exhausted. The tap water purifier marketed by Aquarium Pharmaceuticals is an example of a small de-ionization filter that uses disposable mix bed resin cartridges. The cost of each cartridge is around $20, but they filter less than 50 gallons per cartridge before becoming exhausted. Certainly, this is an impractical solution for anyone wanting to produce purified water for a reasonably sized aquarium system.

On the other hand, passing water through a DI stage after it has passed through an RO unit produces water with DI purity, but since the RO unit leaves so little for the DI stage to remove, it lasts much longer than stand alone DI units.

Source: Sidebar on http://www.wetwebmedia.com/ca/volume_2/cav2i4/RO_systems/reverse_osmosis.htm


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## TWood (Dec 9, 2004)

I bought one of THESE last year and it works okay for my needs. I like having the little 4 gallon capacity pressure tank because I only use RO for top-off in the aquarium. I installed the RO faucet at the kitchen sink and use it to cut tapwater for tea, the bird's water, and such.

Since you are going to be remixing the RO water with tapwater, or reconstituting it with "pollutants" anyway, then taking it to 98% pure (or 100% using DI) is a pointless waste if it's just for plants. For special fish, maybe, but even then...


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## Brilliant (Jun 25, 2006)

TWood said:


> I bought one of THESE last year and it works okay for my needs. I like having the little 4 gallon capacity pressure tank because I only use RO for top-off in the aquarium. I installed the RO faucet at the kitchen sink and use it to cut tapwater for tea, the bird's water, and such.
> 
> Since you are going to be remixing the RO water with tapwater, or reconstituting "pollutants" anyway, then taking it to 98% pure (or 100% using DI) is a pointless waste if it's just for plants. For special fish, maybe, but even then...


I have something just like this under my sink for drinking water.


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## werner (Jul 6, 2006)

Hey TWood- I've got the same one! I use it for drinking water, but not the aquarium.


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## banderbe (Nov 17, 2005)

I recommend http://www.abundantflowwater.com

Buy the 100GPD ReefMaster RO/DI unit. $175 shipped and it works like a dream. 0 TDS, 0 Conductivity water. Doesn't get any more pure than that.


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