Thoughts on "Nano" Reverse Osmosis Systems

[chazman113]

I'm considering buying one of these so-called "nano" RO units on ebay.....

http://cgi.ebay.com/75GPD-AQUARIUM-...in_0?hash=item3a4a9423fd&_trksid=p3286.c0.m14

Its going to be for makeup water and occasional changes to a 30 gallon tank, so its only a gallon or so needed every few days. From what I can see the advantages are:

*space savings
*ease of maintainance
*price

and the disadvantages are:

*no di unit
*r/o membrane will probably last less time due to lack of prefilter stages

I'm thinking its a good match for me because....

*I don't need that much water
*Have limited space under my sink
*My water isn't bad out of the tap
*Dont need SUPER clean water (fish & inverts with plans for simple-to-keep corals in the future)

Has anyone ever had experience with these smaller systems?

 

[Tang Salad]

It seems like that unit is only "Nano" in the sense that it lacks the extra prefilter and DI stages. The membrane is still a 75 GPD... so it doesn't have a "Nano" rate of output. Keep in mind that the extra prefilter stages are there to protect the membrane, so it's possible that the only significant difference with this unit is that you'll need to replace the membrane sooner.

Unless space under your sink is extremely limited, I think you'd be better off getting a full 4 or 5 stage unit.

 

[Toddrtrex]

And space under your sink might not need to be an issue. You can hook up your unit directly to a faucet --- only having it hooked up when you need to use it. I have been doing it that way for years. When you are done, just make sure that the line are all above the highest point of the unit ---- too keep it from drying out --- and you will be fine.

 

[chazman113]

I agree that the membrane will last less time, but looking at the prices on ebay we are talking about $70 vs $110, so even if the unit only lasts about 2/3 the time, there is the convenience of just being able to junk the whole unit and just buy a new one. Maybe I'm hard on them, but I find I somehow break them or they get rusty before the membrane is really "dead". I think in any situation its almost always worth it to just buy a new one if you have to replace filters, di, and the membrane. Keep in mind I'm talking about ebay prices not retail , I assume in a pet store ro units are expensive.

 

[fsn77]

You may get lucky, using a compact RO unit like that and having relatively low tap TDS, but it never seems worth it to me to risk the health of corals / inverts or potentially leave a tank open to nuissance algae just to save a little money and skimp on water quality. Sure, the TDS might be low, but there's no guarantee that what is making up that TDS reading is always going to be the same and/or safe over time.

A RO membrane on a full size unit can last 3 - 5 years ($40 or less), pre-filters 6 months or so ($35 or less), and the DI stage a year or longer (<$20 if bought in bulk and filling your own cartridges) -- all dependent on incoming TDS. A decent full size 5 stage RO/DI unit runs about $150 (perhaps closer to $100 on eBay). I'm not sure how any of that adds up to it being worth it to buy a new unit every time instead of maintaining a single unit with just a little bit of quality built into it. Besides, why create the added trash unneccessarily?

There's nothing metal to rust on the RO/DI unit we have, and I've yet to break anything on it. Perhaps investing in a better quality unit from the start would help avoid some of those issues.

 

[reef2]

u can also look into the mighty might from airwaterice.com. alot of people have them on another site and really seem to like them.

 

[luther1200]

I would ask what is your TAP water TDS. You might be able to get away with it if you have a low TDS. But if its over 100 TDS I wouldn't bother with it. EVen then I doubt you will get 0 TDS without a DI.

 

[Macimage]

I would pass on it and get a better quality unit. Just because your tank is a nano tank does not mean it doesn't need good quality water. The one prefilter will cause your RO membrane to fail prematurely and without a DI and more prefilters, it just doesn't seem like a good idea.

The "nano" designation by that eBay seller does not mean it's a unit for a nano reef tank (not at 75 gpd). I guess by "nano" he means the unit is small.

Joyce

 

[chazman113]

I'de be interested to see how long one prefilter actually degrades the life of an ro membrane as opposed to three. If it wasn't significant, you could argue the cost of the extra prefilters (which you have to change more often) balances it out. Just a thought. It seems we agree that no matter what the prefilter, the ro membrane should spit out the same results, but degrade faster.

 

[luther1200]

I only have a 4 stage, so its a sediment-carbon-RO-DI. And I get 0 TDS no problem. FWIW I replaced my prefilters in February and I still get 0 TDS. And the DI just barely has any color change yet. I think I can last a year easy with my prefilters, and maybe 1.5 yrs. with the DI. So thats about $25 a year for filters and DI.

 

[addicted2reefin]

the r/o will spit out the same results... for about 2 weeks. then u will get major tds creep from the gunk built up in the r/o that shouldnt be there. also without a di, the nitrates from ur tap are not getting pulled out. my nitrates where i am are 30 ppm coming out of the tap!!! no di=shitty tank. at airwaterice or thefilterguys u can get a 4 -5 stage for 100 bucks. i would go for that. the first prefilter takes out solid particles, the second takes out chemicals. with only one prefilter u are screwing ur membrane, and watever is built in will leach over time. im with everyone else, buy a better unit.

 

[Toddrtrex]

<a href=showthread.php?s=&postid=15491761#post15491761 target=_blank>Originally posted</a> by luther1200
I only have a 4 stage, so its a sediment-carbon-RO-DI. And I get 0 TDS no problem. FWIW I replaced my prefilters in February and I still get 0 TDS. And the DI just barely has any color change yet. I think I can last a year easy with my prefilters, and maybe 1.5 yrs. with the DI. So thats about $25 a year for filters and DI.

Not to argue, just to show how different things are. I just changed my pre-filter and carbon block after 3 months. Not because of any TDS issues, but because of pressure issues. My pressure is normally around 62 PSI, but it had dropped down to 40 PSI --- which meant it was taking longer to make water. I changed them both (( sure I could have gotten by with just the pre-filter now that I am thinking about it, and will do that next time )) and my pressure is back up to 62 PSI. What is odd is that my starting TDS is around 150, so my water isn't that bad.

 

[luther1200]

Thats odd. I guess I am lucky, if I open my tap all the way my pressure is in the 80's psi. I run it at 65-70psi.