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Reverse osmosis

I am going to buy a reverse osmosis system and would like advice on a particular system that I have found on ebay.  It claims 100 GPD output, which is a bit of over kill but "what the hey".
The web address is;

http://cgi.ebay.com/ws....01&rd=1

The "buy now" price is $99 + $30 S&H.
-Do any of you have experience with this particular brand?
-Do any of you see any problem with the specs on it?
-Are there any other systems out there that you would recommend?
Any other info on R/O systems would be helpful.
 
Still working on RO units? hehe
Ok my thoughts..
Never expect the rated output from any system. They are rated at a certain pressure and water temperture which is usually not what most people can supply to the unit so expect about 50-75% of the rating depending on what your water temperature and pressure is. This is not a fault of the system so don't hold that against the one your looking at here.
It is always best to get a unit with much more output than you will need.

Comments on the system in your link.
6stage with DI is extreame overkill. The price is good. What I like about the system is that it takes standard prefilters and RO membranes.
You can simply eliminate the extra stages or when the those filters are needing replacing, simply remove them and don't replace them. All you really need are 3 stages.

I would get the unit. Use it (without the storage tank as it reduces RO output as it pressurizes). Use the Post filtering Carbon and DI cartidge and then get rid of them when they needing replacing. When the Prefilters need replacing use a good 1micron prefilter (not a 5micron like it comes with) and a solid block carbon filter.

Tony
 
Aren't RO units extremely wasteful of water because of the flushing needed?  (No, this is not the toilet topic.)  I thought a solar still makes sense, real cheap, no moving parts.  What do you use, Tony?
 
As far as I know, most RO units use about half the amount it produces for backflushing the membrane. So for a gallon of water, you waste 1/2 gallon. I know nothing about this solar still stuff, but I can't imagine it's space or time-efficient. I'd love to be wrong about this!

I love my RO filter, and can't imagine life without it!

Capslock
 
Solar stills are pretty neat but you need the sun around alot! For someone using a few gallons a week it might be feasible. RO units do waste a fair bit of water. Depends on the set up and operating peramitters how much. A 1:1 ratio would be considered pretty good. I use RO units right now as this really is the only way to get enough water in a cost effective manner for me. (I will be setting up a rainwater collection system when I build new structures though but this adds it's own set of headaches.) The way I look at it the RO isn't really that bad.. I pump the water out of the ground and any water that goes out the waste side goes right back onto the ground. There isn't really anything wrong with the 'waste' water.. The dissolved minerals are just a bit higher now.
T
 
Yeah, I think my RO system as it came factory wasted 3-4 gals for every one it made. I added this permeate pump kit which is supposed to as one of the benefits reduce waste water by as much as 80%. If you are further worried about the waste of water... There is another thing you can add where the "waste" aka "brine water" is pumped into your hot water heater to be used in the house...
Andrew
 
[b said:
Quote[/b] (Capslock @ June 26 2004,4:56)]As far as I know, most RO units use about half the amount it produces for backflushing the membrane. So for a gallon of water, you waste 1/2 gallon. I know nothing about this solar still stuff, but I can't imagine it's space or time-efficient. I'd love to be wrong about this!

I love my RO filter, and can't imagine life without it!

Capslock
average is 3 gallons of wasted water for each 1 gallon of produced water. I would hook up the used hose to 50 gal barrels or something, and use the waste water to water your garden.

Filters need replacing usually every 6 months, but you dont replace the R/O membrane (I think). DONT use warm water! just a few drops of water over 85º F. is enough to ruin the membrane!
 
[b said:
Quote[/b] (Spectabilis73 @ June 25 2004,9:34)]Filters need replacing usually every 6 months, but you dont replace the R/O membrane (I think).
Depending on a number of factors membranes usally last 2-5 years.
Andrew
 
  • #10
[b said:
Quote[/b] ]Filters need replacing usually every 6 months, but you dont replace the R/O membrane (I think).

Correct, the actual R/O membrane will last a long time (I've gone years with no ill effect to my CPs and I have REALLY hard water). The cheap pre-filters are the what you need to keep an eye on, even then, mine have lasted a considerably long time with no problems. All things considereds, R/O is the best choice for water system in my life, makes both drinking water, water for my plants, it makes enough, and without all those darned plastic bottles!
 
  • #11
Yeah Tony, still trying to make up my mind.

You mention getting rid of the storage tank as it slows down production.  My R/O needs are about two gallons a day plus enough for two cups of Costa Rican coffee.  In that case, would there be any reason not to hook up the tank?

I agree that six stage is overkill and I like your idea about just eliminating the extra stages when the original ones need replacing.  Also 100 GPD is real overkill unless I start washing my car with it.

You mentioned that it takes standard prefilters and RO membranes.  I did not notice that feature and am glad you did.  That can save a bunch of money.  Thanks for the advice.

What irritates me is that every other three stage system costs a bunch more than this six stage.  Logic would seem to suggest that a three stage should cost only a little more that one-half of the price of a six stage.  Its' a jungle out there.  Mumble, mumble, mumble.
 
  • #12
Well there are some differences in some of the other units you looked at. RO membranes are rated for rejection rate. The higher rate the more they cost. Also the prefilters and post filters used. The unit your looking at on Ebay at least uses a carbon block prefilter but it's only rated for 3000 gallons which is about as low as you can go. It will work just as fine as one with a higher rating but they did cut cost a little there.. and a little with the 5micron sediment prefilter.
Generally speaking the cost of the unit is in the plastic housings and the RO membrane. So that's why there is not a huge difference in price for a 3 stage unit. But when you look at spectrapures 9000 gallon carbon block prefilters and 1micron sediment prefilter along with their 98%+ TFC membrane you start upping the price significantly vs the 95% TFC membrane in the EBay unit.

That 3% difference won't be noticable by your plants or your coffee.

As for the storage tank. You could use it without any problem. It just means your going to waste more water but for the little water you need it probably won't make too much of a difference. What happens as the RO water fills the tank it gets pressurized as the pressure in the tank approaches the pressure of the water going into the RO unit less of the water gets pushed through the RO membrane so more water goes down the waste side.

The standard RO membrane size and prefilter canisters are a big deal though. That will allow you to shop around for prefilters and replace the ro membrane down the road when needed without any difficulties. Disposable line filters.. like the post DI filter on the unit your looking at are a big waste of money when needing replacing. You don't need it anyway so no point spending money on it later ;>

Tony
 
  • #13
I have a 5 stage system with a 24 GPD membrane.  The storage tank holds just under 4 gallons.  I use this for my humidifier, for drinking and cooking and for my plants (inside and in the g/h)  For the most part it keeps up.  Just before I bought the RO system I started saving the bottles from the distilled water I was buying..   I took the time to fill those bottles up and now if I run out I use those then just refill them over the next couple of days...  Works just fine for me.  
smile.gif
 So if you have a 100 GPD membrane...  your storage tank would fill up even faster than mine...  I would think it would be able to keep up.   If I drain my tank and leave it dripping in a container, I can get a gallon in 20 mins.  I have not rechecked this since I added the permeate pump...  It supposedly speeds up water recovery rate by up to 400%....   Hope that info helps put the supply into perspective...
Andrew

Edit: Here is the info on the permeate pump if you want to read about it...   It helps solve the problem of more waste as the tank gets fuller....  And has other advantages also.  http://www.wattspremier.com/watts....CATID=1
 
  • #14
<span style='font-size:12pt;line-height:100%'>I have been using various water purification technologies for a very long time.

I recently purchased a 2" dia x 26" long membrane designed for high recovery at very low pressure. This membrane is a replacement for the original TFC (thin film composite) membrane that came with this R.O. pressure housing. Back in 1994, when I originally obtained this unit, it was using a membrane rated for about 50 GPD using standard household temperature and pressure and for each gallon recovered, 9 gallons went down the drain -- of course since it used a TFC membrane that was sensitive to chlorine it also required a carbon pre-filter. To illustrate how this technology has improved: the replacement membrane can produce 240 GPD and only wastes about 5 gallons for every gallon produced. It still needs protection from chlorine, but "what a difference". When I need a quick gallon of purified water I can get it in 5-6 minutes instead of 50-60 minutes. Waste water is never wasted here in the desert . . . it works wonders augmenting drip irrigation of landscape plants and fruit trees.

I am awaiting a 600 gallon storage tank where I shall store the water, it will then be pumped through a UV sterilizer and pressurized in a rubber bladder holding tank. It will be piped into the greenhouse to be used to water my CP collection from their own pure water faucet and special hoses and to cool/humidify the air using a cyclestat timer with a high-pressure booster pump and fog nozzles.

It will also be piped into the house and dispensed at a special sink faucet and to the automatic ice-maker.

We get our water from a community CO-OP system and they have good points and bad:
--they rarely chlorinate as there is no real need for it
--water is initially quite good (200ppm)
--sometimes their system has equipment (pump) failures (outages) so having a backup supply (600 gallons in storage - pre-purified) can really be essential to keeping my CP alive and well.</span>
 
  • #15
[b said:
Quote[/b] (Lauderdale @ June 26 2004,7:48)]Yeah Tony, still trying to make up my mind.

You mention getting rid of the storage tank as it slows down production.  My R/O needs are about two gallons a day plus enough for two cups of Costa Rican coffee.  In that case, would there be any reason not to hook up the tank?

I agree that six stage is overkill and I like your idea about just eliminating the extra stages when the original ones need replacing.  Also 100 GPD is real overkill unless I start washing my car with it.

You mentioned that it takes standard prefilters and RO membranes.  I did not notice that feature and am glad you did.  That can save a bunch of money.  Thanks for the advice.

What irritates me is that every other three stage system costs a bunch more than this six stage.  Logic would seem to suggest that a three stage should cost only a little more that one-half of the price of a six stage.  Its' a jungle out there.  Mumble, mumble, mumble.
its not really overkill unless you're willing to wait an hour for just one gallon of water... If you dont feel like monopolising the faucet for 5 hours just to fill a 5 gallon bottle, it really isnt overkill... I get a gallon for each ten minutes of water. You're not going to be able to wash a car with it, because it doesnt come out as fast as you think... You turn the faucet to only just a dribble
confused.gif
 
  • #16
I just hooked up a RO unit and am concerned about its efficiency before I use the water on my plants. I am going to take a water sample to the aquarium store later today and was wondering what kind of results I should look for.
Thanks,
-Nick
 
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