RODI question.

[-TS-Vash]

I got a new 100 gpd tfc membrane today in the mail it was in a plactic bag with air in the bag and my tds reading is the same and sometimes worse than my tap water. Don't you have to seal them? And do you ship them wet or dry?

[-TS-Vash]

Come on guy no one knows?

[kzoo]

PM sent

[Buckeye Hydro]

Originally posted by -TS-Vash
I got a new 100 gpd tfc membrane today in the mail it was in a plactic bag with air in the bag and my tds reading is the same and sometimes worse than my tap water. Don't you have to seal them? And do you ship them wet or dry?

One you get that membrane wet, keep it wet. They can be stored dry indefinitely as shipped.

Now - on to your system. So the tds in your tap water and in your post RO (pre DI) permeate (not waste water) are equal?

Its a good bet that your membrane is not fully seated. Open the housing, pull the membrane out and check to see that the orings around the stem at the far end are ok. Check to assure the brine seal - the big black gasket around the entire membrane - is ok as well.

Now reinstall the membrane, and make sure that once you feel the membrane stem hit the far end, you push it in about another 1/2 inch. That will seat the orings.

Try that and let me know how it worked.

Russ @ BFS

[-TS-Vash]

I installed the membrane and i checked to make sure it was in right and the seals were good and seated right. i ran it for 7 hours and it is still at 35 tds just like my tap only now the di resin is trashed and has changed color it is new and has never been used. I installed it right out of the bag the big bag full of air and ran it for hours. I guess it was no good from the store.

[Buckeye Hydro]

Your carbon block is in good shape, right?

[-TS-Vash]

All my filters are new never used i just replaced them all along with all the fitings and tubes.

[-TS-Vash]

Some info on my ro its a 100 gpd zero % waste water its 6 stage and all the filters are new. So your saying that the tfc membrane could be sent bone dry in a large bag full of air? My tds before and after the membrane is 35 the same and my di resin is after that and makes no change now because it was trashed and changed color.

This is a link to the one i have.
http://cgi.ebay.com/New-Reef-6st-100...QQcmdZViewItem

[Buckeye Hydro]

Right. We ship Filmtec membranes dry everyday. I can't tell you anything about the membrane that originally came with your system. Is your replacement membrane of the same brand?

I don't have much good to say about that unit, other than I'll bet it didn't cost you much!

The sediment filter/carbon filter array is configured incorrectly. The system has no pressure gauge so there's no way for you tell when your prefilters are clogged.

I wonder if you left the original carbon stages in too long and allowed chlorine to get to your membrane?

Your system has a knock off brand membrane with no brand name specified (that should be a warning signal to you if you ever buy another system). The ebay ad claims in one place the rejection rate is 98 to 99%, and in another 93%. That's a troublesome indication the vender doesn't understand the concept.

It has a small and horizontal DI cartridge. Nonrefillable? Another fundamental configuration flaw.

It has a GAC stage after the DI stage - yet another configuation flaw.

Has a mix of fitting types - not that the fittings are bad, its just an indication of a system that has been scabbed together from a imported system intended for drinking water.

We do a steady flow of business replumbing/reconfiguing these ebay systems once people understand what it is they bought.

Russ @ BFS

[AZDesertRat]

Besides the fact it is a pretty low end system utilizing questionable components, it is NOT zero waste or anywhere near it. It wastes 4:1 or thereabouts just like almost every other unit on the market. The low price should be a clue to those looking for a good RO/DI, when the total cost of the unit is just slightly higher than a high quality Dow Filmtec RO membrane costs that should be a great big RED FLAG! Unfortunately with the filters they supply I seriously doubt you will ever see anywhere close to 0 TDS even with a tap water of only 35. They are very poor quality.

[CinciCobra]

So is a unit like this salvageable? I mean could a guy install the correct membrane, refigure the filters, and be all set?

[AZDesertRat]

Honestly I would be concerned about the quality of the housings and fittings and the fact they may split or leak at any time. At a price like that they aren't much for quality. I have not seen that particular unit personally but I have seen and worked with others very similar and they leave a lot to be desired. Some knock off stuff is OK but I don't believe there is a single part on that unit that meets WQA, NSF or ANSI standards and that worries me. Quality standards are there for a reason and its to protect the consumer.

[-TS-Vash]

First off it is 0% waste water the rodi unit only produces waste when i back flush it and i have had the unit for a year and the tds was 001 the whole time when the tds got to 002 i changed the filters and let the tfc membrane run dry so i got a new one and its bad. The unit is great and as for the fittings i just changed them all to the higher quality ones. It's not a problem i got a membrane made by mws with us dow materials. Its on the way. I think if i said its 0% waste water that i would know if it is or not dont you think?

[-TS-Vash]

Looks like to me it could be the same housing as any other ro unit i have ever seen i should know i worked for a LFS for a year and have seen most of the ones on the market.

Simple question SHOULD THE MEMBRANE BE SENT WET OR NOT. And the question was answered. Thanks.

[Tang Salad]

Can anyone explain how it's possble for an RO unit to have 'zero' waste water?

[-TS-Vash]

spectrapure makes one.

[AZDesertRat]

Its not possible. The only manufacturer that regularly sells one is Watts Premier and its not really 0 waste, it plumbs it into the hot water heater and is limited to about 15 GPD. In the picture you posted the orange line coming from the flow restrictor is the waste line, its impossible to have zero waste without that line being open or it equalizes pressure on both sides of the membrane and it does absolutely nothing at that point.
Spectrapure does not make one. They do make a total DI system that does not produce waste but like all DI systems it has a limited life in comparison to a RO/DI unit. They like all vendors are working on a reduced waste system but as I said before you cannot make a RO unit with 0 waste, something has to keep the membrane flushed or it plugs rapidly.

[Tang Salad]

Originally posted by AZDesertRat
You cannot make a RO unit with 0 waste, something has to keep the membrane flushed or it plugs rapidly.

Thanks, that's what I thought. It just doesn't seem possible.

[-TS-Vash]

DUDE i know if the water drains down The drain. The line is only used to flush the membrane i have one and the store i use to work for has 2 get a life. I THINK I WOULD KNOW IF THE VALVE WAS OPEN AND WATER WAS GOING DOWN THE DRAIN. I have used it for a year. Thats why i dont like to post on here there is always some smart *** like you that thinks he knows every thing.

[Tang Salad]

Relax pal, nobody is saying you "WOULDN'T KNOW IF THE VALVE WAS OPEN AND WATER WAS GOING DOWN THE DRAIN."

I asked the question only because my understanding of how RO filters work precludes the possibility that one would work well if it did not produce waste water. Maybe my understanding is just dead wrong. Maybe yours is too. And maybe someone can come along and explain it...

Also, wasn't your problem that your " tds reading is the same and sometimes worse than my tap water" ?

So you seem to be saying that your RO, which produces no waste water, also does nothing to filter the water. Perhaps these two facts are related?

[CinciCobra]

Originally posted by AZDesertRat
Honestly I would be concerned about the quality of the housings and fittings and the fact they may split or leak at any time. At a price like that they aren't much for quality. I have not seen that particular unit personally but I have seen and worked with others very similar and they leave a lot to be desired. Some knock off stuff is OK but I don't believe there is a single part on that unit that meets WQA, NSF or ANSI standards and that worries me. Quality standards are there for a reason and its to protect the consumer.

Understood - thanks for the clear answer.

I have the opportunity to pick up one of these units almost free, and debated on changing to a higher quality membrane and calling it a day. I may still do it, and live in the same city as buckeye field supply who maybe could do some tweeking on it. Just some more info for an informed decision you gave me, so thanks alot!

[The Grim Reefer]

Originally posted by -TS-Vash

OK I am a realative newbe when it comes to RODI so maybe there is a reason for this. Isn't the square unit with 2 fittings in and out the auto shut off valve for the waste line? This unit looks to have it hooked up to the RO feed line and to the processed water line running to the DI rather than the waste line. Is there a reason for this or is the unit plumbed wrong?

[Buckeye Hydro]

Maybe a little background information about RO systems and the particular unit TS-Vash uses will help clarify things. No offense intended at all.

The RO membrane housing has three ports - the one on the end that unscrews is the "in," or supply port. After water passes through the prefilters it flows to the RO membrane through this port.

Water has two ways to exit the RO membrane housing. You'll see these two ports on the other end of the RO membrane housing. One port is near the center of the end (this is the permeate ("purified water") port). The other port is near the edge of the end (this is the waste water port).

RO membranes are actually a spiral wound device consisting of multiple layers - only some of which are the semi-permeable layers that purify the water. Other layers are designed to allow water to pass from one end of the membrane to the other without passing through the semipermeable membrane. This water that passes from one end to the other without making it through the semi-permeable membrane provides for water flow over or across the membrane to flush it during use. In fact, most of the water entering the "in" port flows over the membrane rather than through it. In a properly configured system with working components, for every 1 part of water that goes through the semi-permeable membrane, about 4 parts pass from one end of the membrane to the other without going through the semi-permeable layer. This is the water you hear folks referring to as "waste water."

It's true that this water isn't useful in your aquarium, but it serves an important purpose in the functioning of the membrane. Without this flush water, or "waste water," all the impurities in the water (some of which we commonly measure as Total Dissolve Solids, or TDS) would be captured within the body of the membrane. Because most of these contaminants are too large to go through the semi-permeable membrane they would accumulate in the membrane and the membrane would produce less and less permeate as scale accumulates.

So to avoid this situation, ALL reverse osmosis systems allow waste water to pass "over" the membrane rather than through the membrane.

So let's go back to those two exit ports I mentioned above. For water to make it to the permeate port, it must go through the semi-permeable layer of the membrane. This layer of course provides some resistance to the water passing through. So, "looking" for the route of least resistance the water goes out the open waste port where there is next to no resistance to flow. In this hypothetical scenario - all of the water coming into the RO membrane housing would go out the waste port. Obviously this wouldn't result in the production of permeate. So to force some water to go through the semi-permeable membrane, we partially block flow through the waste port. We do this with what is called a "flow restrictor." The amount of flow the restrictor allows is about 4 times the amount that will go through the semi-permeable membrane. This is why the restrictor needs to be "matched" to the capacity of the RO membrane.

When the restrictor partially blocks flow through the waste line, water "backs up" in the RO membrane housing, pressure builds, and some water is forced through the semi-permeable membrane and results in the purified permeate you use in your aquarium.

TS-Vash's system uses a device that is essentially a modified ball valve. Turned in one direction it presents a typical flow restrictor to the waste flow. Turned in the other direction it allows unrestricted flow through the waste line. You'd turn it to this position to "flush" the membrane (to a greater extent than what happens with the more typical 4:1 flush the membrane sees under normal operating conditions).

TS-Vash - if indeed little or no water passes out the waste tube during normal operation of your system, either you likely have a defective flow restrictor (not unheard of), a clogged flow restrictor (not uncommon).

If your system produces little or no waste water, the membrane will be damaged by the premature accumulation of scale as described above.

With your new membrane and prefilters - assure:
*you get about 4 times as much waste as permeate (you may need a new flow restrictor), and
*replace your carbon block regularly so you don't expose the membrane to chlorine
*use a pressure gauge to assure adequate pressure is reaching the membrane (i.e., assure that none of your prefilters are clogged)

As an aside (and as AZDesertRat referred to), there are no "no-waste" RO systems. "Waste" water is part and parcel of the RO membrane technology.

What you may be thinking of is a system that one of the US vendors sells that routes the waste water to a pump, where it is forced under pressure back into the supply plumbing.

Other "no-waste" systems used in this hobby include prefilters (sediment and carbon) and DI resin - no RO membrane, so no waste water.

AZDesertRat - thanks for taking the time to offer your help to TS-Vash.

Wow - that turned into a long post. Clear as mud? I'll try to answer whatever questions come up.

Russ @ BFS

[Buckeye Hydro]

OK I am a realative newbe when it comes to RODI so maybe there is a reason for this. Isn't the square unit with 2 fittings in and out the auto shut off valve for the waste line? This unit looks to have it hooked up to the RO feed line and to the processed water line running to the DI rather than the waste line. Is there a reason for this or is the unit plumbed wrong?

The auto shut off valve is plumbed correctly, assuming there is a check valve within the elbow fitting in the permeate port.

Normally the auto shut off valve and the web of tubing are installed behind the RO membrane to provide a more finished appearance.

Russ @ BFS

[purza_00]

Thankyou Russ for the detailed explanation on RO/DI system operation. In aquarium use, with a system like pictured above, shouldn't the post DI carbon filter be removed/disabled?