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any suggestions for RO units?

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islanddog

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Mar 17, 2004
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I am looking at getting a RO unit.... under 50gpd. Does anyone have any suggestions or recommendations? It seems most people use just a RO unit without DI. Is there huge advantages to having both or a combined RO/DI unit?

I appreciate the input!

Kevin
 

Stircrazy

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Feb 5, 2004
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BC, Canada
the only real suggestion I can give you is to buy as big of a membrane as you can afford up front. the difference between 50 gpd and a 100 gpd unit should be less than 50 bucks. I upgraded my 100 gpd to a 320 gpd unit and I love being able to pound off almost 13 gal of water in 1 hour.

as for DI you can always add that later if you feel it is necessary.

Steve
 

jazznreef

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the DI membrane is expensive and it wastes a lot of water. i have the kent ro/di s "maxima". i like it but it wastes over three times the clean water it produces. i'm not so sure i would go that route again.
 

NaH2O

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I also own a Kent Marine. I love to see the water go in at TDS reading in the high 300s - high 400s and come out at 0.

Personally, I feel the DI is important. The RO will remove your big contaminants, but the De-ionization will remove things like silicates, phosphates, and nitrates that get past the RO.
 

acropora

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West Hempstead, N.Y.
jazznreef said:
the DI membrane is expensive and it wastes a lot of water. i have the kent ro/di s "maxima". i like it but it wastes over three times the clean water it produces. i'm not so sure i would go that route again.
While it is true thar R.O units have a high waste water to pure water ratio(4 to 1).D.I units do not waste any water. A D.I. filter is the last stage filter before the water enters your system. As Nikki stated above they are a great addition.There are many who also use two D.I. filters to increase output purity.
 

Stircrazy

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NaH2O said:
Personally, I feel the DI is important. The RO will remove your big contaminants, but the De-ionization will remove things like silicates, phosphates, and nitrates that get past the RO.
actually the membrane removes silicates, phosphates, and nitrates very well. I would only recommend a DI if when you test your RO output there are still a couple PPM of hardness left.

Steve
 

Ed Hahn

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Kevin at Aquatic Dreams sells a really nice unit. It is very reasonable. Kevin even added a modification to the unit. I would highly recommend it. Shop around then talk to Kevin. I have not seen anything that compares to his deal yet on his RO/DI unit.
 

DonW

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Lowes in Lakewood had one last night marked down to $50. For that price you could just upgrade the filters. As far as I can tell it is the same as the Kent 25gpd wo/di. I know the home center filters do not filter down as far. Most are 5 micron but the .5 microns will fit just fine.

Don
 

jazznreef

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acropora: "to di or not to di" is a legit debate. some feel the extra filtering from a di unit is not worth the expense and environmental concerns that comes from a 4/1 waste to clean water ratio. i'm pretty sure anthony calfo's coral prop book discusses this although i couldn't find the referance just now. i guess what one decides depends on the water quality from the start, cost of water at your local muni and your concerns for the environment (which might depend on the water availability in your area).
 

cdeakle

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Lynnwood, WA
I currenlty use and would recommend the Kent Marine Maxxima Hi-S RO/DI 35GPD unit. I have used it for 2 years or so now and it has proven to be in my top 3 best purchases for this fine hobby:

1) AquaC Urchin Protein Skimmer
2) Kent Marine Maxxima RO/DI Unit
3) Premium Aquatics Refractometer
 

fishermann

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Searcy, Arkansas
DI DOES NOT WASTE!!! the waste comes from the RO membrane. The flow through RO/DI unit is 1. particale cartridge, 2.carbon cartridge, 3. RO membrane, 4. backdown through the DI cartridge. The RO membrane is where the waste water is from, the DI is just a final filter cartridge. Our water has about 40 ppm going in and around 5 or 6 coming out of the RO unit, and 0 coming out of the DI unit, but more important is what nikki said about sil., phos. and so forth. Sometime drink some water that is just been thru the first three and not the DI unit. It is still sweet, once it goes through DI it doesn't taste so good anymore. I got my unit from cirrus technologies in Fla. They are a reef central sponsor. ph. # 407=814-7333. You should talk to John there, they can build it anyway you like. Mine has a flush system which is very important to flush the RO membrane so it last alot longer, also i can get water out of the RO without going through DI for drinking water. The RO membrane is what cost, not the others, but if flushed a couple times a month it should last for 4 or 5 yrs. The added expense for a 100 gal. unit is well worth it because as the RO membrane starts to go bad it slowly plugs up and flows less, so if you can make more to begin with it well last longer, its filtering capabilaty does'nt deminish, it the flow rate that goes down.
 

mojoreef

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Easy john easy:lol: .
I think now days DI is becoming more and more required for filtering tap water. many municipalities now days are adding ammonia to the water supply, they do this in order to increase stand time for chlorine disinfection. Most of the ammonia will breakdown but you will still get some, acompaning the ammonia is alot of nitrates, The best RO filter will only pull out about 80% of ammonia ions and about 90% of nitrate ions, so if you put it into the scope of things on all the money and effert we put into controling these two nutrients, I'll just drop the di cartridge into the game and have one thing less to not worry about.

just my two cents.


Mike
 

mattseattle

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cdeakle,

funny we have exactly the same top 3 purchases as far as equipment goes:

1) AquaC Urchin Protein Skimmer
2) Kent Marine Maxxima RO/DI Unit
3) Premium Aquatics Refractometer
 

Stircrazy

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BC, Canada
fishermann said:
Our water has about 40 ppm going in and around 5 or 6 coming out of the RO unit, .
how old is your membrane that is horrible performance for a RO, at 40ppm input you should be getting less than 1 output from your RO. usually people replace the membranes when they show 3ppm or higher and that is with 400ppm input. I myself get 0ppm out of the membrane but I only have 17 to 25ppm going in. I also run dual carbon block to remove chloramins.

Steve
 

mattseattle

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yeah, mine is 38 going in and 1 going out of the membrane. maybe it's time to flush the membrane. when i first flushed my membrane i did a test on the water and the tds was almost 400. i flushed it till the water coming out was equal to the water going in. i couldn't believe the deposits on the membrane and afterwards my production shot way up.
 

jazznreef

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Just looked up my source and discovered the R/O cartridge is to blame for a high water waste to product ratio rather than the DI process. I mistakenly mixed the two. In Calfo's 'Coral Prop' book page 170 "for aquarists without a use for rejected R/O water, there are other alternatives to water purification like DI units." In this discussion Calfo basically claims the quality of product water is not high enough with the R/O membrane to warrant the excessive high waste ratio. However, he does not discuss units that have DI and R/O capabilities. Do these devices "waste" less water than those with only R/O abilities?

Sorry for confusing the two terms.
 

mattseattle

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I wouldn't think so since the waste water is ejected from the membrane and the 'purified' water is going from the membrane into the DI cartridge. the DI cartridge only purifies the water (taken from the output of the membrane) more.

i wonder if you had a 2nd RO membrane that was fed by the waste water line from the 1st membrane if you would save waste water? i know your output would definitely go up.

i know there are systems that are DI only but the cost is more for the unit and it products 0% waste water.

There is also something called Cold Sterile (i think that is the name) that is 0% waste water and supposely produces water that is pure without taking out calcium and alkalinity. i've read differing opinions on that.

RO/DI in my opinion is far more cost effective than anything I've seen even with the waste water factored in. Alot of people use the waste water to either put into their washing machines or into their pools. I only save a little of it to water my plants, etc.
 
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Stircrazy

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mattseattle said:
i wonder if you had a 2nd RO membrane that was fed by the waste water line from the 1st membrane if you would save waste water? i know your output would definitely go up.
yes this is how mine is set up, I have the waist water of the first feeding the second so I adjust my overall good to waist ratio at 1:2 so I only waist 2 gal for ever gal I make.

if your water is low in tds you can get away with this but if it is high it will cause your second membrane to fail early.

Steve
 

acropora

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Mar 14, 2004
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West Hempstead, N.Y.
jazznreef said:
acropora: "to di or not to di" is a legit debate. some feel the extra filtering from a di unit is not worth the expense and environmental concerns that comes from a 4/1 waste to clean water ratio. i'm pretty sure anthony calfo's coral prop book discusses this although i couldn't find the referance just now. i guess what one decides depends on the water quality from the start, cost of water at your local muni and your concerns for the environment (which might depend on the water availability in your area).
Sorry, I haven't had a chance to reply;but fishermann had my back.:) I live in West Hempstead,Long Island,N.Y. and the water could be better.Another problem is rust in older plumbing.I use a Spectrapure R.O./D.I. unit and in addition to the standard pre-filters;I have added a .35Micron washable/re-usable sediment filter before the RO unit.This stand alone unit increases the life of all filters down stream and can be easily washed and re-used.
 
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