RO/DI driving me crazy!!

[AlexKilpatrick]

I have replaced all the filters in my RO/DI. My sediment, carbon and DI are a week old, maybe 8 hours or so of use. My RO membrane is a couple of hours old. I am getting 250 in to the system and about 230 out of the RO membrane. I'm sure it is hooked up right, and I have run it for several hours to clear up the membrane. Any ideas? I can't imagine why this isn't working, and how an RO membrane could do so little.

[JimD]

Like I said before, check the tds of the ro output, that will tell you the condition of the membrane. Chances are the DI is spend from the old membrane.

[AlexKilpatrick]

I am checking at the output of the RO membrane. The output *before* the DI is 230, so the whole system up to the DI is giving me a 20 point drop. This is a brand new membrane.

[hobogato]

sounds like it is a bad membrane then - mine did the same thing, only after about 6 months of use. talk to the company you bought it from and they will probably replace it.

[matt]

I take it you have the flow restrictor in place on the waste line, right? Are you familiar enough with these filters to know for sure if you're getting the right amount of flow? What's typical with a 75-100gpd filter and decent water pressure is a steady stream out of the waste and either a fast drip or just enough to be more than a drip out of the output. There should be something like 2-3 times the flow out of the waste that's coming out of the output. If the waste is shooting out like crazy, you're just flushing the membrane. Just for laughs check the TDS on the waste. When that doesn't work, assuming you know all the stuff about the flow and are certain it's hooked up right, it has to be a bad filter membrane and I hope you can get a free replacement!

[AlexKilpatrick]

Thanks for the advice, I do appreciate it.

I have an adjustable flow restrictor on the waste line. If I set it wide open, I still get what is probably too much output -- a slow flow, not really a fast drip. I initially thought maybe the membrane wasn't seated, but it definitely is. Just to clarify -- the o-rings go to the input side, right? (I can't imagine it would work the other way)

The TDS of the waste is the same as the output of the RO.

[AlexKilpatrick]

sounds like it is a bad membrane then - mine did the same thing, only after about 6 months of use. talk to the company you bought it from and they will probably replace it.

6 months? I would be happy with 6 months. This is how it worked from the beginning.

[hobogato]

^^alex, the guy i got mine from said it should last at least a year.

[OldSalty]

Get rid of the adjustable flow restrictor. Talk to brian at purely h20 and get the correct flow restrictor. I have the adjustable one too and have been thru 3 membraines in 2 years. I'm trashing it as per brian. Believe me, your membrains should last at least 3 years provided ya keep the filters changed. To do that correctly you need to test for chlorine. If your test kit measures ANY it's time to replace the carbon filters. Filter life also depends on how much water your using. Those of us that have auto-top-off systems will of course be replacing them sooner. Probably at 3 months. Your chlorine test kit will tell you. I myself am SICK of replacing membraines so I watch my filters very close now.

Good luck
Kelly

[Bill S]

Have you checked your TDS meter?

[Instar]

IF the flow restrictor is on the waste line and its much at all, it will blow the membrane. They work slowly and only to a certain specific pressure. The resticted oraface where the waste line attaches is all the back pressure it needs. Back pressure from the water drain line ( a plug or valve) will definitely blow the membrane out and since water pressure changes, often a lot during the day, it is a recipe for trouble. In all my lab days, we never have run a waste line restrictor valve on any RO unit and the membranes last forever. I've never heard of using a waste line restrictor valve, that must be a new thing to get home users to have to buy new membranes once or twice a year?

[AlexKilpatrick]

Have you checked your TDS meter?

Yep, I have two meters and they both read the same.

[AlexKilpatrick]

IF the flow restrictor is on the waste line and its much at all, it will blow the membrane. They work slowly and only to a certain specific pressure. The resticted oraface where the waste line attaches is all the back pressure it needs. Back pressure from the water drain line ( a plug or valve) will definitely blow the membrane out and since water pressure changes, often a lot during the day, it is a recipe for trouble. In all my lab days, we never have run a waste line restrictor valve on any RO unit and the membranes last forever. I've never heard of using a waste line restrictor valve, that must be a new thing to get home users to have to buy new membranes once or twice a year?

Maybe the reef RO/DI systems work differently. On my system, if I didn't restrict the waste flow at all, then I got no output at all. Most newer RO/DI systems come with a waste restrictor built into the waste line, so a lot of people may not be aware they have them.

[matt]

IF the flow restrictor is on the waste line and its much at all, it will blow the membrane. They work slowly and only to a certain specific pressure. The resticted oraface where the waste line attaches is all the back pressure it needs. Back pressure from the water drain line ( a plug or valve) will definitely blow the membrane out and since water pressure changes, often a lot during the day, it is a recipe for trouble. In all my lab days, we never have run a waste line restrictor valve on any RO unit and the membranes last forever. I've never heard of using a waste line restrictor valve, that must be a new thing to get home users to have to buy new membranes once or twice a year?

Every aquarium R.O. filter I've ever seen ( which is not that many, but several) has some sort of restriction on the waste flow, which I assume puts some pressure on the membrane. On my purelyH20 filter, the flow restrictor is a valve; when it's open and there's unrestricted flow out the waste line, it's acting as a membrane flush kit. Other R.O. units I've seen have a little plug inside the waste hose right where it attaches to the filter.

[Instar]

Built in restrictors are a lot different than a valve. The valve is not necessary and is actually a clever trick. How can you adjust it properly for your unit without a flow meter and pressure gauge?

Have you actually hooked up a flush kit? It is not the same as a waste line restrictor valve being open.

[matt]

My flush kit, at least that's what Bryan told me it is, is just a valve, more like a switch I guess, on the waste tubing. Flip the switch one way, flow is restricted and the filter works normally, flip it the other way and water flows through the waste tubing like it's coming out of a fire hydrant. That's when it's flushing the membrane.

BTW, are you still raising clowns? I'm looking for a pair of true percs, really little ones.

[OldSalty]

All RO units are the same in the way that they work. They MUST have a flow restrictor on the waste line to function correctly. You can use a valve BUT it must be presisely adjusted for the membraine GPD it is used on. Trouble is what is the correct adjustment? When I got my first unit (75GPD) from Aquatic Reef (Now Purely H2O) There was a formula they gave me on how to adjust it. I never really got it correct, hence, BLOWN MEMBRAINES! Point is, Get the proper flow restrictor (NOT A VALVE) It installs inside the tubing of the waste water line. Heck, if you wanted to, use the adjustable flow restrictor valve you replaced as a flush kit. To do this you need 2 tee fittings. Come out of the waste line to the first tee, come out of the tee with a piece of tubing and install the flow restrictor in it and hook it to the second tee. Continue the waste line out of the second tee to your drain of wherever you were draining. Now come off your tee and install the valve you removed and conect the other side to the 2nd tee. Make sure the valve is CLOSED. To flush the membraine just open up the valve for a couple of min. I flush mine 3 times a week.

[Instar]

A flush kit is a set of tubing and valves. Perhaps we are talking about different kinds of flushes? The one used to dislodge large molecules from the pores of the membrane, essentially cleaning the the membrane itself, runs the unit in reverse flow so the water goes the opposite direction through the membrane.

(Yes matt, I am raising clowns. My true percs are awesome, not spawning yet though. I will have 2 different color patterns when they start. The pairs are getting to look pretty mature, so it shouldn't be too long.)

[matt]

I get the feeling that flushing the R.O. membrane does not involve reversing the flow through the membrane, as you would expect in a typical mechanical filtration scenario. I'm pretty sure it works a little differently, something like flushing by moving water faster on the same side of the membrane, which reduces pressure on that side and encourages anything caught in the membrane to end up in the water flow.

Anyhow, my "flush kit" is a switched valve, off or on, that I assume is tuned to the specific membrane that my filter has. So, in theory it works exactly the same way as the flow restrictor. I have to say, when I've pulled those little plug type restrictors out of the waste tube on other filters, they don't look they would be very accurate, but what do I know.

Larry, I'm going to send you a PM about some clowns.

[AlexKilpatrick]

How is a valve different from a flow restrictor? Don't they both restrict the flow?

With respect to measuring, it seems to me that as long as your waste / product ratio is high enough (> 4 from what I have heard) you are fine. Most RO/DI systems that are for sale now have a pressure gauge that you can use to measure the pressure on the membrane, although I don't know what a "safe" pressure is.

FWIW, the flow restrictor on the system I just bought was way too high. I was getting a 1:1 product:waste ratio.

[OldSalty]

1 to 1 will destroy your membraine FAST. And NO, a flush kit does not reverse flow. Like I said it is just a valve and tubing. the flow restrictor goes in between it, hence the 2 tees. To flush the membraine just open the valve. Alex, you can call and talk to brian about the formula on how to adjust it but, I speak from experience. get a proper flow restrictor, there less than 4 bucks. your membraine will last a long time (provided you change the filters.

[matt]

Something still doesn't sound right to me regarding your 230 TDS, though, even if you had the wrong flow restrictor. I would think that if anything it might wear out the membrane (just guessing) but not cause total failure this quickly. After all, it's still basically set up the same way; you have some pressure on one side of the membrane that is primarily determined by your household water pressure. Mine is quite high, almost 80PSI, and the filter works fine. The only thing the flow restrictor is really going to change is how quickly the water moves through the housing. Again I'm just kind of guessing, but I think it's a pretty good guess. In any rate, you bought it with that flow restrictor in place, right? So whoever sold it to you is responsible?

If I remember, the way you described it seemed like you had zero TDS for a few weeks, which probably was the D.I. cartridge, but that got exhausted really fast, probably because your R.O. membrane didn't do anything, then 230.

I forgot if you bought this filter new and if there's some sort of warranty on it. If not, call Bryan or send him an email, alert him to this thread, and I bet he'll help you out in some significant way.

[AlexKilpatrick]

Sorry, I know this is confusing. My RO/DI is about 5 years old, and I was getting 230 TDS out of it, even after replacing all the filters and the membrane. I had 0 TDS for a few *hours* before it shot back up to 230. I spent several hours trying to fix it, but for all I know it has some design flaw or something else wrong with it (although I don't know what it could be) and it has been producing 230 TDS water for a year or more.

Unfortunately, I am extremely busy right now with work and I am being paid by the hour, so this was an expensive delay for me. It was more economical for me to just say "f*** it" and replace the whole thing, which is what I did. The new one works fine and produces 0 TDS water, but when I tested the flow restrictor new out of the box, it was at 1:1. It had instructions on how to fix that, which I did.

At some point in the future, I will spend time messing with the old unit and see what it wrong with it.

[AlexKilpatrick]

1 to 1 will destroy your membraine FAST. And NO, a flush kit does not reverse flow. Like I said it is just a valve and tubing. the flow restrictor goes in between it, hence the 2 tees. To flush the membraine just open the valve. Alex, you can call and talk to brian about the formula on how to adjust it but, I speak from experience. get a proper flow restrictor, there less than 4 bucks. your membraine will last a long time (provided you change the filters.

Just to clarify my understanding, does a flush kit temporarily remove any restriction on the waste line? Does it do anything other than that?

[OldSalty]

1 to 1 will destroy your membraine FAST. And NO, a flush kit does not reverse flow. Like I said it is just a valve and tubing. the flow restrictor goes in between it, hence the 2 tees. To flush the membraine just open the valve. Alex, you can call and talk to brian about the formula on how to adjust it but, I speak from experience. get a proper flow restrictor, there less than 4 bucks. your membraine will last a long time (provided you change the filters.

Just to clarify my understanding, does a flush kit temporarily remove any restriction on the waste line? Does it do anything other than that?Yes, It bypasses the flow restrictor, (the water just flows around it) Thats all it does. Note also that on a new system with an adjustable flow restrictor you will have to set it up (adjust it) thats why It came on 1 to 1 as you stated. As you close the restrictor you get more product water, opening the restrictor gives less product water. It is adjusted so the product water matches the GPD of the membraine. Now it only makes sense that opening the restrictor to far will cause excessive waste water. Close'ng it down to far will cause excessive pressure across the membraine which it turn will destroy it (causes holes and tearing) in fairly short order. Like I said before, get rid of the adjustable one and install the capilarry type that goes in the drain line, then you don't have to worry if it's adjusted correctly. I've done Alot of research on RO/DI units. There is one other important thing I'd like to point out to those of you that use DI. When a RO unit first comes on there is an extremly high TDS for the first min of so. this happens untill the pressures sorta equlize across the membraine, You can see this with a TDS meter. After about 1 min you will see it settle down and produce the correct ratio. Now if you dump all that 190 to 200 tds water into your DI quess whats goint to happen to it. Yup, it eats it up fast. Better to install a bypass valve on the DI to flush out all the high TDS before it flows thru the DI. Once it settles down then pass it thru the DI. Makes it last MUCH MUCH longer.

Kelly

[Bill S]

Well, all this discussion had me go checking one of my units - and it AGAIN has the same TDS out as in... The membrane is only 3 months old. The unit is a piece of junk - IMO, from Coralife. I bought my other one, which is has been FLAWLESS from www.aquasafecanada.com, about 2 years ago. I've emailed them for another 100gpd membrane ($35 plus shipping), but I THINK the problem is the restrictor on the Coralife. Aquasafe units come with a flow restrictor that doesn't have to be adjusted. I MAY just end up replacing the whole thing. For $85 plus shipping, then I don't have to fool with the piece of junk.

[OldSalty]

Thats the only way to go. As far as the other one, yes the membraine is GONE. Probably due to the flow restrictor. BTW, just a note, I found a 50GPD unit at McCoy's lumber for about 60 bucks, came with the 4 gallon tank too. When I took it out of the box I found that the waste line was connected to the membraine in and the actual membraine out was the drain, so point is to educate yourselves on how these units work and check even new ones to see if there plumbed correctly. The only reason I was able to notice this was because I did a ton of research on RO units and how they work.

[AlexKilpatrick]

ok, I am getting really tired of messing with RO/DI now. I was better off when I was ignorant.

I bought a new system. I adjusted the in-line flow restrictor (by cutting it), but when I adjusted it down as far as it would go (maximum waste flow), I was only at 3:1. They recommend a minimum of 4:1. I put in a valve instead, and left it at about 8:1 or so. I had to produce a lot of water for a big water change. For the first 10 hours or so, it was TDS of 0, which was fine. I let it run overnight, and when I got up this morning it was 76 (verified with two different meters).

I must be dense or something, because this is just not working out for me.

[OldSalty]

8:1 is WAY off, no wonder you have had problems. 3:1 is GOOD. Something doesn't make sense to me. You say you adjusted it down. That would mean MORE product and LESS waste. Remember if you close the flow restrictor you get more product water, but if you close down to far you will BLOW the membrains. Did you open it up as far as it would go? If thats the case you will get poor water quality out. Also if its now reading 76 after the DI then the DI is now TOTALY exausted. I quit using DI, IMO it's a waste of money. I now use DOUBLE carbon. TDS is around 5 ppm. One other thing Alex, Why did you cut the flow restrictor? I don't see why you would do that. Was it built in to the line? If so, that's your problem, get another one, re-install it and you should be fine. 3:1 up to 5:1 is good. With waste flow like that it's the same as flushing the membraine all the time which is a BAD thing to do.

[AlexKilpatrick]

8:1 means less pressure on the membrane. The documentation says a *minimum* of 4:1. The flow restrictor in my unit is a long capillary tube. If I cut it, then it reduces the restriction on the waste line, which in turn decreases the amount of product, increases the waste flow, and puts less pressure on the membrane.

I don't understand why opening up the waste line would decrease the water quality. I can see that it would make the product rate go down, but I don't see why it would make the water quality lower. It still has to pass through the membrane.

It could be that my DI is exhausted. I will check that. I have been trying to err on the side of caution and not blow my membrane.

[OldSalty]

Yes that is true, but why would you want 8:1? your just wasting a lot of water and also throws off the pressures the units needs to function correctly. The flow restrictor that was installed was put there for that membraine. Don't mess with it, just use the unit like it was intended. Get another flow restrictor , put it in and leave it alone, you will be ok. I think you might be trying re-engineer the unit and it don't need that. Measure the TDS at 8 to one then adjust it between 3 to 5 to 1 and measure again, you will see a much lower TDS because an RO membraine needs a min of 40psi to work. So if you open up the drain line all the way the pressure inside the membraine drops. Your basicily bypassing it. Thats the best way I can explain it, which as I hope you can now see thats why you have had so much trouble with the unit. If you have the correct restrictor and you keep your filters changed ofter there is no reason why the membraine won't last 3 or more years. Remember I have been thru 3 membraines because of this, so I know what I'm talkin about.

[Bill S]

Here's the quote from my guy about the adjustable flow restrictors:

"...the adjustable back pressure is a scam....instead of a properly sized flow restrictor, they give an adjustable... guess what... the homeowner wants to save money and turns it either off or to a stetting that is too low...result...bad water and bye bye membrane...great way to create business...."

[OldSalty]

I REST MY CASE!!!

[BuckeyeHydro]

Keep your adjustable restrictor.

Sounds like an easy fix here - I'll bet your RO membrane is not fully seated - pull it out and inspect the small rubber orings at the far end. With a flashlight also inspect the small plastic "cup" into which the RO membrane stem inserts in the far end of the housing. Assuming the orings are ok, and the membrane housing is OK, then simply re-insert the membrane until you feel it hit the far end. Then with the heel of your hand, push hard and turn, and you'll feel to membrane go in another 1/2".

[BuckeyeHydro]

"...the adjustable back pressure is a scam....instead of a properly sized flow restrictor, they give an adjustable... guess what... the homeowner wants to save money and turns it either off or to a stetting that is too low...result...bad water and bye bye membrane...great way to create business...."

My goodness. I don't think there is any business-generating scam going on with adjustable flow restrictors.

Can you adversely affect your system if you don't set it correctly? Sure.
Can you adversely affect your system if you set it wrong purposefully? Sure.

Can you get peak performance out of a system with a correctly adjusted flow restrictor? You bet.

Adjustable flow restrictors are not a good choice for a point-of-use system where the operator wants to set it up and walk away (like a typical drinking water set up under a sink). They can be a very good choice for a hobbyist.

Russ @ BFS

[Bill S]

Sorry, Russ, but I TOTALLY disagree. Just look over these posts, and talk to people about RO/DI systems. Many get disgusted because they can "...never get it working right...". Destroying a membrane and the DI resin just to save a couple of $$ on water? Give me a break. I'll take the non-adjustable every time - and I couldn't possibly recommend the adjustable type of restrictor to ANYONE.

[BuckeyeHydro]

I respect your opinion Bill.

Half the posts above seem to be people having trouble with capillary flow restrictors.

If you have an adjustable flow restrictor, and you want a non adjustable one, that's easy. Never make an adjustment to the needle valve that is an adjustable flow restrictor and viola - you have a static flow restrictor.

A couple of pointers on adjustable flow restrictors: They are inteded for people who understand the systems and want peak performance, especially when the tap water temperatures change through the seasons. They are not intended for people who want to pay next to no attention to their system.

Don't fret about tuning the restrictor to a precise 4:1 ratio. Its not that critical - anything between 3:1 and 5:1 is ok. If you have a static flow restrictor - check the ratio during the dead of winter - you won't have a 4:1...

The idea of an adjustable restrictor is not to save water - it is to keep the ratio at about a 4:1 to maximize production, even when the conditions (in this case water temperature) are far removed from the factory specs (77 degrees F feed water)

If you have one and don't want it, by all means set it at a ~4:1 in the summer and never touch it again (it thereby becomes a static restrictor), or replace it with a static restrictor. They are cheap and super easy to install.

If you install a capillary type restrictor, you can buy one that is pretrimmed for a x gpd system (assuming you have 50 psi water, 77 degree water, and 250 ppm water), or if your conditions don't match factory specs of your membrane, you can buy an uncut capillary restrictor and trim it to length yourself to get your system at an apx. 4:1.

Russ @ BFS

[Bill S]

Wow. With all of the other things I have to worry about, "tuning" my RO units for feed water temperature changes? I have a hard enough time changing all of the dang 9 volt batteries in my smoke detectors on the "spring/forward, fall/back" events!

[BuckeyeHydro]

:lol