RO/DI system question

[kerry]

I have a question about DI filter replacement. At what PPM do you guys change the DI filter media? Mine has just started to read 1-2PPM TDS. I am only using it for top off as you all now I have scrubbers so I dont water change. My tanks (all three) usually need about 4-6 gallons per week for Kalk top off. Is 1-2 PPM TDS bad enough to change the DI media?

[Ace25]

Change the DI. Anytime you get a 1+, the DI is spent. Yes, 1 TDS is considered "bad". The reason being is at 1 TDS, you know some bad stuff it making it all the way through the filter, and you have no idea what it is. It could be benign like calcium, or could be bad like copper or other nasty chemicals. It is the "unknown" aspect that makes any TDS reading become questionable, and in this hobby, water is not something you really want to have to question and worry about if you can help it.

General rule of thumb for RO membranes is 10% of what the tap water TDS is. If your tap water TDS is 500, the water coming out of the RO membrane should be no more than 50 (90% rejection rate), ideally more like 25 (95% rejection rate). If the water coming out of the RO membrane is above 10% of what your tap water reads, that means it is time to replace the membrane. Back flushing the membrane extends the life by A LOT, and a $10 flush kit from Bulk Reef Supply is a must have, makes it so easy to back flush the membrane in seconds, which I do before and after every time I run my RO/DI filter. You can keep a bad membrane and just replace DI more often, but that ends up being more costly in the long run because the DI resin will get spent fairly quickly if it has a high TDS going through it.

[kerry]

Thats what I had been doing, when it got to 1 I was changing it. It takes about a year to get to 1 PPM as I have pretty decent water out of the tap, if I remember correctly it was 32 or 42 PPM out of the tap or maybe that was out of the fridge that has one of those cheesy carbon filters in the water supply line which I cant imagine removes much TDS anyway. Before the DI the RO is 4 PPM.

[Garf]

My water out of the tap is about 450us. I recharge when DI reads 1us. I've read somewhere(something to do with RHFarley) that as soon as DI is spent, all types or nasties are released.

[Floyd R Turbo]

What happens with DI is spent is that certain ions have a greater ionic strength than others. So if there is unused DI media available, all is good. Once the media is fully used, whatever ions have a weak bond will be released when something else with a stronger bond comes along. IIRC the things that get released are high up on the list of what you don't want released. Ammonia and phosphate come to mind, but I can't recall exactly.

What I will be doing shortly is adding a second DI chamber to my setup. This way, I don't have to wait until one is mostly used up but not completely. I can just wait until one is completely used, then switch the DI out on that one and switch the canister order or just replace the beads in the first one whenever I get a chance, either way no chance of my DI burning out

[Garf]

What happens with DI is spent is that certain ions have a greater ionic strength than others. So if there is unused DI media available, all is good. Once the media is fully used, whatever ions have a weak bond will be released when something else with a stronger bond comes along. IIRC the things that get released are high up on the list of what you don't want released. Ammonia and phosphate come to mind, but I can't recall exactly.

What I will be doing shortly is adding a second DI chamber to my setup. This way, I don't have to wait until one is mostly used up but not completely. I can just wait until one is completely used, then switch the DI out on that one and switch the canister order or just replace the beads in the first one whenever I get a chance, either way no chance of my DI burning out

I recharge my DI with HCL and sodium hydroxide. The beads are good for at least 2 years. However, I work at an electrophoretic paint deposition plant and I can get my hands on these chemicals easily. I can see how things may become more complicated if these chemicals are not readily to hand. Recharging only takes 2 hours tops.

[Floyd R Turbo]

I thought you had to have your DI separated out into cation and anion to be able to recharge. I use BRS nuclear color changing resin, it's cheap and lasts long anyways (since i only use it for top-off water, no PWCs)

[Garf]

I thought you had to have your DI separated out into cation and anion to be able to recharge. I use BRS nuclear color changing resin, it's cheap and lasts long anyways (since i only use it for top-off water, no PWCs)

Separate by adding 16ish % sodium hydroxide. The anion will float after a while. If it doesn't drain the solution and add some more sodium hydroxide. Separate the anion and cation (pour the anion into separate jug). Rinse the cation very well till all traces of hydroxide are gone.fill the cation jug with 16%ish of hydrochloric acid. This will recharge the cation beads( stir every 30 mins for 2 hours ). Rinse both containers with r.o. ( I suggest 10 litres of rinsing, 1 litre at a time ). Ther are detailed methods of D.I. RECHARGING if you google it.

[Ace25]

Floyd, not sure which way you were thinking of using 2 DI canisters but my experience is I have not had good luck with using 2 DI containers back to back, they seem to both go bad within days of each other. I believe the reason is once the first DI container is all used up, you get all that nasty stuff then being released from the first DI canister and dumping into the second canister, which makes the DI resin get used up VERY quickly. I have found it much better to only have 1 DI and have an inline TDS meter and have a second canister loaded and ready to go so when I do see a 1 TDS I can swap out the canister in a few seconds. That may be the way you were describing doing it, just wasn't sure so wanted to share my experience.

I will skip on recharging, I am not comfortable enough playing around with those chemicals all over a couple dollars worth of DI. If a person has access to the chemicals and comfortable doing it, by all means go for it, just not for me.

[Floyd R Turbo]

To me that makes no sense, but I guess I haven't tried it before. Theoretically, using 2 DI canisters would be exactly the same as one larger one. In mine, the resin changes color from blue to brown when it gets used up. The brown separates into 2 distinctly different colors and one sinks to the bottom, the other stays in the middle, and the blue unused resin stays at the top. So the water passes through the used resin first, which would 'release' the weaker ions and those get picked up by the unused resin at the top. When this is used up, the released ions would just go to the next DI canister like it was more media in the same canister. So what am I missing?

[Ace25]

On mine, the first canister gets "used up" 100% before the second color changing canister even starts to get used. Not sure what the science behind that is, all I know is when I use 1 canister and replace when TDS hits 1, the new canister last just as long as it should, but when I daisy chain them together and leave the bad DI canister inline as the first canister, the second "new" DI resin will be all used up within just a couple days. Only way to fix that issue is have an inline TDS meter BETWEEN the 2 canisters so you know when the first one goes bad, but that really isn't saving anything doing it that way, otherwise you really don't know when the first one is spent and spitting out 1+ TDS into the second canister. Of course, 1 TDS into a DI cansiter isn't really an issue, but usually once you start to see 1 TDS, 10-25 TDS is usually just a few more gallons away. At my work we use giant 4' DI bottles and they get used up in less than a month and we have to run the water for 5 minutes every day to "flush" the DI because it is usually 2x as high as tap water TDS (tap=700+ TDS, DI=1500+ TDS unless flushed) if you let DI resin sit in water for any period of time.

[Garf]

To me that makes no sense, but I guess I haven't tried it before. Theoretically, using 2 DI canisters would be exactly the same as one larger one. In mine, the resin changes color from blue to brown when it gets used up. The brown separates into 2 distinctly different colors and one sinks to the bottom, the other stays in the middle, and the blue unused resin stays at the top. So the water passes through the used resin first, which would 'release' the weaker ions and those get picked up by the unused resin at the top. When this is used up, the released ions would just go to the next DI canister like it was more media in the same canister. So what am I missing?

I wouldn't rely on colour changing resins. A TDS meter in the us range is a much better than a ppm.

[Floyd R Turbo]

Interesting Ace. I guess I find that result to be the opposite of what I would have expected, I would not think that passing the water through used resin would make any difference on the end result as long as there was unused resin after it. After all, this is exactly what is happening in my one canister setup.

I don't rely on the color changing resin for TDS, I rely on it to tell me when I should start paying more attention to my TDS.

[Ace25]

Believe me, I thought EXACTLY like you are thinking as well, which is why I did put 2 DI canisters back to back. It took me a couple refills to figure out it was not working like I expected it to. Thinking about it more, and with my experience at work, I think I know why it doesn't work.

If water sits in a DI canister, it leaches bad stuff back into the water. On a normal home RO/DI system you are supposed to back flush the membrane before and after every use and you're supposed to let the clean water run for a minute or 2 before collecting. If you let the filter sit with water in it (like you connect/disconnect or use a float valve but only have water running though every couple days) then all the bad stuff in the DI canisters get released. That 1500 TDS that is sitting in the first canister gets pushed right into the second canister, in turn severely shortening the lifespan of the resin. When my resin was completely exhausted, getting 1 TDS, my first canister looked near 100% used up/color changed, but the second canister looked 90% good going by color, but TDS told a different story.

[Floyd R Turbo]

yeah your 1500 TDS part is where you lose me though, my tap TDS is 500-650, and out of my RO membrane it's under 30. So running tap water through DI, of course that's going to burn that out like nuts, but we're not doing that. I know what you're saying happens when the RO membrane sits there, which is why I tap off the RO outlet and drain about a gallon of water out before engaging my DI, and that water will fire out at >80 then slowly ramp down to below 20. But then when I flip the valve to go through the DI bed and sit there and watch the TDS out of the DI, even after a week of sitting there and no water running, it rarely jumps up above 5 or 6 and then ramps down to zero within less than 1 changeover of the DI chamber. I never see the TDS going as high as double the DI input

[Ace25]

That is opposite of what I experience with DI that has been sitting for a few days, it is always way higher than tap water TDS until the water that is in the DI canister gets flushed out. On a home unit, it isn't that much, but it is a short term spike, but still I think that really reduces a secondary DI filter if placed in line, just a waste of DI from my experience. I get much more life just using a single canister than using dual.

On a DI only canister that is 4' tall, there is A LOT of water sitting in there stagnant which is why I see 1500 TDS for up to 5 minutes running the faucet on full open. If the DI canister didn't spill bad stuff into the water, then I shouldn't see much higher than tap TDS, but I see way higher and the company that replaces the DI bottles even said that is how DI works and needs to be flushed daily or else the water coming out will be much worse than tap water. I was told the only way to avoid the issue is to drain the water out of the DI after each use, but that is not a realistic solution IMO.

quote I found:

DI resin can and does release stored up TDS even before it is exhausted. Weakly ionized substances don't have a strong electrical charge or bond so start sluffing off and get released back into the treated water. These include silicates, phosphates and nitrates just to name a few and none are what you want in your reef.

[Floyd R Turbo]

Well since I am the king of valves, I would say that what I should do to solve this is flush the RO membrane like I have been doing (and I need to truly flush it, with a flush kit, I'm just running the bad water out of it right now) then when that's done, I can open another valve between the 2 DI chambers and flush out the first, then when that's clear flush out the second, and then start making water. Since I make water 40 gallons in one shot without shutting it off, I figure this will work OK. Still trying to wrap my head around the whole problem with 2 DI chambers but maybe it's the flushing part that was missing, because let's say you run them 100% all the time, it really should be no different running 2 separate chambers than it would be running one larger one as long as you never let the water sit stagnant or as long as you flush them as described. What do you think, does that make sense?

[Ace25]

I agree, if you put a flush valve in between the 2 DI canisters that should solve all the issues I am speaking of. :D

[Garf]

Ace25 - I suggest you tell your boss that the people supplying your resins are a bunch of jokers and get some proper suppliers in. They are either telling you lies, supplying spent resin, regenerating resins with sub standard chemicals or a combination of all three. A fully charged mixed bed should never leach dissolved solids. Separate anion and cation chambers do leach some solids, but these are recircularory systems and continually reprocess the same water,in effect replicating a mixed bed by by repetition. These are also regenerated as previously described.
Floyd - you are right, two connected mixed beds is the same as one longer mixed bed.

[Ace25]

Good to know Culligan can't be trusted. I will inform the state of California, my employer.

BTW, just got home and did a brand new test. Tested TDS of my tap water, then I took the DI canister off my RO/DI unit, pulled the DI container out of the canister, and let the water drain into a cup that was sitting in the DI container. I last used my RO/DI filter on Saturday, 4 days ago. Results:

Tap water = 560 TDS
DI canister = 1330 TDS

Soooo.. maybe I won't be talking to my employer after all. ;)

After running water through RO/DI filter (7 stage Seachem w/ BRS filters, Spectrapure membrane) for 30 seconds post membrane flush, TDS = 0. It is that 1330 number that gives me the greatest concern. It proves to me without a doubt that bad stuff does get released from the DI resin back into the water if it sits. A 30 second flush of the DI chambers seems to solve those issues though, so it isn't a big deal as long as you do that 1 step.

Here is the thing I am a little confused about. When you put 2 DI canisters back to back, my thinking is canister 1 does ALL the work until the DI is all used up, then canister 2 takes over, because in theory it should be 0 TDS once it comes out of the first canister. So why did BOTH of my DI canisters get used up within days of each other, multiple times? Went through 8 bags of DI resin in a year because of that, now I go through 4 in a year. I would think having 2 separate canisters would not = 1 larger chamber because 1 canister can get the water to 0 TDS all by itself.

[Floyd R Turbo]

I can attest to at least the fact that the stagnant DI water is above zero. not 1330, but definitely not zero. Actually I haven't tested the stuff right out of the DI in a while, I usually let it run for 30 seconds before even bothering. Next time, I will test it!

[Garf]

I have a question about DI filter replacement. At what PPM do you guys change the DI filter media? Mine has just started to read 1-2PPM TDS. I am only using it for top off as you all now I have scrubbers so I dont water change. My tanks (all three) usually need about 4-6 gallons per week for Kalk top off. Is 1-2 PPM TDS bad enough to change the DI media?

I would suggest reading this. It contains everything you will need to know;
http://reefkeeping.com/issues/2005-05/rhf/index.php

[Ace25]

Good stuff in that link.


Several issues arise relating to the depletion of the DI resins that aquarists need to be aware of. Primary among these is that when a DI resin becomes depleted, that does not simply mean that the water passes through just as it came from the RO effluent. It may actually be much worse from an aquarist’s perspective. The reason for this is that while the DI resin is functioning properly, all ions will be caught. But when it is depleted, not only the new ions are coming through and might show up in the product water, but so are all the ions that ever got into the DI resin in the first place. The total concentration of ions coming out of the exhausted DI resin will not be raised as compared to the RO's effluent, but which ions are released may be very different.

In the DI descriptions above, I did not address the fact that some ions will show a greater preference for attachment to the resin than will others. When the resins are not depleted, it does not matter what the ions’ affinity is, as all are bound. But in a depleted scenario, when there are more ions than ion binding sites, those with a higher affinity for the resin will be retained, and those with a lower affinity will be released. It turns out that silicate is found at the lower end of affinity for anion resins. Consequently, if the DI resin has been collecting silicate for a long period and is then depleted, a large burst of silicate may be released.

Perhaps even more of a concern is ammonia. In a system with chloramine in the tap water, the DI resin will serve the important function of removing much of the ammonia produced by the chloramine breakdown. Ammonia has a poorer affinity for many cation-binding resins than do many other cations (e.g., calcium or magnesium). Consequently, when the DI resin first becomes depleted, a big release of ammonia from and through the DI resin is likely. I recently had a DI resin become depleted, and the effluent contained so much ammonia that I could easily smell it.

Other complications can also impact resin depletion. One potentially important issue is that the anion and cation-binding sites may not become depleted at the same time. Figure 10 shows this scenario when both types become depleted together, with sodium and chloride in the effluent. But, it is possible for one to become depleted first, and in that case, the pH of the effluent can swing far from neutral. Figures 11 and 12 show what happens when a lot of carbon dioxide is present, as is the case with some well waters. Initially, it is mostly bound as bicarbonate, and the effluent is essentially pure water. Note, however, that as the bicarbonate is removed, the anion binding resin is being taken up with bicarbonate, while the cation-binding resin is unchanged and is therefore not being depleted.

[Garf]

Good stuff in that link.

He certainly knows his stuff. You never want to process water through a spent system. And due to the instablility of pure water, testing is fraught with variables. However, the science proves the technology. Hats off to Randy.

[akando]

since we are on the RO/DI thread, I recently replaced all my filters and membranes on my system when I moved to the new house. my set up is a follows Sediment>Carbon>Carbon>RO>DI>DI. My tap water is around 400 TDS according to my hand held digital meter. Coming out of the RO, TDS is about 6. After the DI stage, upon start up it is 19 but after running for a few minutes it goes down to 9. I made 130 gallon of water and the TDS still reads 9. What am I doing wrong?

[kerry]

Not sure? I run mine just like that but only one DI unit. My tap is 30-70 TDS at any given test. After the RO its about 4 TDS average even after a year and now the DI is showing 1 TDS after a year.

[Garf]

since we are on the RO/DI thread, I recently replaced all my filters and membranes on my system when I moved to the new house. my set up is a follows Sediment>Carbon>Carbon>RO>DI>DI. My tap water is around 400 TDS according to my hand held digital meter. Coming out of the RO, TDS is about 6. After the DI stage, upon start up it is 19 but after running for a few minutes it goes down to 9. I made 130 gallon of water and the TDS still reads 9. What am I doing wrong?

Does your TDS meter read 0 when you dry it and expose it to air?

[akando]

garf, yes it does.

[Garf]

garf, yes it does.

I assume that the D.I filters are not new ones.

Are they full of water, without large air bubbles?
Is the flow rate through the canister similar, or slower,than it was with the previous membrane?
Are you sure the tubing etc, has been connected up correctly?
Did you "Break in" your new membrane, to remove any preservatives to waste?
Were you having TDS issues before you replaced your filters?

It may seem tedious sending multiple posts, but you need to eradicate the simple faults that can appear before a "Replace your resin" quote is made.

[akando]

The DI Filters are Brand New.The first one is full of water, the water flows into the second one but doesnt accumulate.

Flow rate I am unsure about since I switched from a 150 GPD set up to a 90 GPD membrane.

I am almost positive tubing is hooked up correctly. I put a 90 GPD restrictor in when I installed the new membrane. I payed attention to all the IN and OUT markings on the Canisters.

I did "break in" the Membrane.

I did not have a TDS meter at the previous house, I started to notice a pressure drop and had a little tax money left over so I decided to just change everything when I moved.

Thanks for your help.

[Garf]

I don't understand why water is not filling the second chamber. Please check inputs and outlets and MAKE The 2nd chamber fill up. You may discover then that the first one isn't hooked up correctly also. If you can't find a fault, try to post a close up picture of resin chambers and pipe work.

[Floyd R Turbo]

+1 no reason the 2nd chamber should not be filling, even if you hooked it up wrong. Theoretically if the 2nd chamber isn't filling you shouldn't be getting anything out of it. I guess it depends on the chamber type that you're using, I use standard RO canisters

[Garf]

+1 no reason the 2nd chamber should not be filling, even if you hooked it up wrong. Theoretically if the 2nd chamber isn't filling you shouldn't be getting anything out of it. I guess it depends on the chamber type that you're using, I use standard RO canisters

The only way I can see this happening is if the D I canister is a flow in one end, flow out the other type and he has the input at the top and outlet at the bottom. Therefore the D I media is full of air and not water.

[Floyd R Turbo]

Yes that would make sense, in that case flip the canister over and in the bottom out the top, done.

[akando]

I double checked the in and outs and they are correct. The first DI cartridge has started to change colors at the bottom. Both cartridges have arrows pointing up so I know they are in right. I'm stumped.

[Ace25]

Unscrew the canister that won't fill with water, fill it to the top with water yourself and put it back on, try again. That problem happens all the time on my BRS Dual media reactor when I used it.. anytime I did a water change and air got pushed into the reactor the second chamber would take DAYS to fill back up, and that was with a 1200 GPH pump.

[Floyd R Turbo]

Oh I think I know what could be happening. If you have an insert that is filled with the DI resin which has the "in" side on the bottom, and there there is water going into the chamber, but the outside of the chamber is not filling, then the air is trapped. The water fills the bottom of the chamber and then pushes up through the resin insert. What I do when I start with an empty chamber is turn the canister upside down and let it fill from the "top" until the water fills the outside section, then turn it right side up and the inner chamber fills. Do this for one, then flip over again for the second one.

Still doesn't explain your problem, but at least your chambers will fill up with water.

[Garf]

I double checked the in and outs and they are correct. The first DI cartridge has started to change colors at the bottom. Both cartridges have arrows pointing up so I know they are in right. I'm stumped.

By having air in the canister, the water pressure pushes up very narrow stream of water through the resin. This quickly burns out the resin in the channel that water is passing through. Although the resin at the top of the canister looks good, you can bet that inside the canister (out of sight), there will be a channel of spent resin that the water is flowing through. This effect is called channelling. Just make sure filters are full of water before you apply water pressure from the R.O. and all should be good.

[Garf]

Ace25 - I see a relationship between the problems you had running chambers back to back, with the problems Akando has. It sounds as though your second chamber was channelling. This would explain all the symptoms you have explained, even though visually everything looked ok. A method of releasing all air entrapment may enable you to double up without concern.

Akando - have you got a relief valve on the top of your chambers. A photo of you system would be ideal.

[akando]

This is my setup.
http://i72.photobucket.com/albums/i200/91dimenc/di%20filter/f203e402.jpg
http://i72.photobucket.com/albums/i200/91dimenc/di%20filter/11264e86.jpg

[Garf]

Have you made sure there is no air in the system. Take the chambers off and gently tap on the floor, refill manually if necessary.When the chambers are FULL retest the output for TDS. if the flow is good and there is no air in the system, and you still get high TDS, the resin is no good.

[Garf]

Are you sure that the yellow line in your photo is the good R.O. and not the effluent that should go to waste.

[Floyd R Turbo]

No I think he's got it right. It's a perspective thing in the pic, the waste line is offset from center, the yellow line is the center line...I think...gotta go look at mine now LOL

[Garf]

It may be an international deviation but my input is in the centre, which means the effluent should be in the centre, and the good stuff on the outside !

[Floyd R Turbo]

That's how his is. Input is on the center right, effluent is near the center left, waste line is on the edge of left which is why you see the waste line on the corner of the left end

[Floyd R Turbo]

Here is mine, 2 systems, one for fish, one for people

http://i611.photobucket.com/albums/tt191/FloydRTurbo/2012%20Miscellaneous/RODI%20System/DSC00778.jpg

count the valves lol

http://i611.photobucket.com/albums/tt191/FloydRTurbo/2012%20Miscellaneous/RODI%20System/DSC00780.jpg

Fish

http://i611.photobucket.com/albums/tt191/FloydRTurbo/2012%20Miscellaneous/RODI%20System/DSC00779.jpg

People

http://i611.photobucket.com/albums/tt191/FloydRTurbo/2012%20Miscellaneous/RODI%20System/DSC00781.jpg

[Garf]

That's how his is. Input is on the center right, effluent is near the center left, waste line is on the edge of left which is why you see the waste line on the corner of the left end

Think we have got mixed up. By effluent i mean rubbish. If the R.O goes into the centre of the filter, the bad water should also come out of the centre, leaving the filtered good stuff coming out of extremities. Looks to me like his "rubbish"" is going through the D.I. While the good stuff is going down the sink.

[Floyd R Turbo]

Gotcha when I think effluent I think product water, or "filtered" water. I believe this is the proper way to refer to it. EDIT it is actually the "permeate" water that is the purified water, and the "concentrate" that is the waste water.

No, you need to look closer at the construction of you RO membrane. There is a hard plastic "spindle" in the center, but on the "input" side, it is not a pass-through. If you look at your membrane, you can't see through the spindle. There is a rubber gasket on the outside of the membrane (over the blue plastic coating) that prevents the water from going from the "in" side directly to the waste drain. The water is forced from the outside of the membrane inward, so on the other end of the spindle if you look into it you will see little holes, and on the end of that spindle are 2 rubber gaskets that "plug" into the hole on the inside of the housing, this is where the product water comes out.

Just one example

http://www.google.com/products/catalog?q=ro+membrane&hl=en&prmd=imvns&biw=1920&bih=887&um=1&ie=UTF-8&tbm=shop&cid=7953618268587518837&sa=X&ei=RyiKT7KIB-rs2QWhtsTNCQ&ved=0CKIBEPMCMAc

cutaway

http://www.waterfilters.net/RO-Membrane-Housings.html

http://www.google.com/imgres?q=ro+membrane+housing&hl=en&sa=X&biw=1920&bih=887&tbm=isch&prmd=imvns&tbnid=Bb53LWYYERAEmM:&imgrefurl=http://www.spectrapure.com/faq_p0.htm&docid=E8V5nh4SaEEdCM&imgurl=http://www.spectrapure.com/jpgs/mem-housing-side-port-view.jpg&w=1185&h=669&ei=viiKT5PSD8jq2QXS-MTkCQ&zoom=1&iact=hc&vpx=1293&vpy=164&dur=413&hovh=93&hovw=164&tx=123&ty=84&sig=109009736577281595378&page=1&tbnh=93&tbnw=164&start=0&ndsp=53&ved=1t:429,r:7,s:0,i:83

http://www.thewatertreatments.com/water-treatment-filtration/hyper-filteration-reverse-osmosis/

Unless they do things differently where you're at, you've got yours hooked up wrong if you are using the center outlet for your good water.

[Garf]

Gotcha when I think effluent I think product water, or "filtered" water. I believe this is the proper way to refer to it. EDIT it is actually the "permeate" water that is the purified water, and the "concentrate" that is the waste water.

No, you need to look closer at the construction of you RO membrane. There is a hard plastic "spindle" in the center, but on the "input" side, it is not a pass-through. If you look at your membrane, you can't see through the spindle. There is a rubber gasket on the outside of the membrane (over the blue plastic coating) that prevents the water from going from the "in" side directly to the waste drain. The water is forced from the outside of the membrane inward, so on the other end of the spindle if you look into it you will see little holes, and on the end of that spindle are 2 rubber gaskets that "plug" into the hole on the inside of the housing, this is where the product water comes out.

Just one example

http://www.google.com/products/catalog?q=ro+membrane&hl=en&prmd=imvns&biw=1920&bih=887&um=1&ie=UTF-8&tbm=shop&cid=7953618268587518837&sa=X&ei=RyiKT7KIB-rs2QWhtsTNCQ&ved=0CKIBEPMCMAc

cutaway

http://www.waterfilters.net/RO-Membrane-Housings.html

http://www.google.com/imgres?q=ro+membrane+housing&hl=en&sa=X&biw=1920&bih=887&tbm=isch&prmd=imvns&tbnid=Bb53LWYYERAEmM:&imgrefurl=http://www.spectrapure.com/faq_p0.htm&docid=E8V5nh4SaEEdCM&imgurl=http://www.spectrapure.com/jpgs/mem-housing-side-port-view.jpg&w=1185&h=669&ei=viiKT5PSD8jq2QXS-MTkCQ&zoom=1&iact=hc&vpx=1293&vpy=164&dur=413&hovh=93&hovw=164&tx=123&ty=84&sig=109009736577281595378&page=1&tbnh=93&tbnw=164&start=0&ndsp=53&ved=1t:429,r:7,s:0,i:83

http://www.thewatertreatments.com/water-treatment-filtration/hyper-filteration-reverse-osmosis/

Unless they do things differently where you're at, you've got yours hooked up wrong if you are using the center outlet for your good water.

You've confused me now because I think the last line of your last post is totally correct.

[Ace25]

LOL, isn't there a MUCH easier way to figure this out, with the persons help of course.

Step 1, collect water out of line 1 and test TDS
Step 2, collect water out of line 2 and test TDS

The line that has very low TDS is obviously the RO output line. Should take less than 1 minute to figure this out in person. ;)

[Garf]

Why do things the easy way when you can talk to your friends for hours on end for no reason. Good one ACE.

[Floyd R Turbo]

Ace you are a total buzzkill man. Sheesh. :)

[Garf]

AKANDO - upshot, make sure your RO output is the correct way round and test your TDS.

[akando]

Yes, RO membrane is set up right. Getting 6 TDS out of it. I'm going to try repacking my DI resin and removing air. Will post result!

[Garf]

Yes, RO membrane is set up right. Getting 6 TDS out of it. I'm going to try repacking my DI resin and removing air. Will post result!

Good move.

[Buckeye Field Supply]

General rule of thumb for RO membranes is 10% of what the tap water TDS is. If your tap water TDS is 500, the water coming out of the RO membrane should be no more than 50 (90% rejection rate), ideally more like 25 (95% rejection rate). If the water coming out of the RO membrane is above 10% of what your tap water reads, that means it is time to replace the membrane.

A little more information on this. Different membranes have different rejection rates specified by the manufacturers. It is these rejection spec's that you should compare to the performance you see from your membrane.

At the risk of information overload, here's the specs on the membranes we are most familiar with.

Russ

http://i224.photobucket.com/albums/dd293/BuckeyeFS/ROMembraneFactorySpecs-1.jpg

[Buckeye Field Supply]

I don't understand why water is not filling the second chamber. Please check inputs and outlets and MAKE The 2nd chamber fill up. You may discover then that the first one isn't hooked up correctly also. If you can't find a fault, try to post a close up picture of resin chambers and pipe work.

remember that DI filters are axial flow cartridges - so he just has some air trapped in the housing - this is very common.

Russ

[Buckeye Field Supply]

By having air in the canister, the water pressure pushes up very narrow stream of water through the resin. This quickly burns out the resin in the channel that water is passing through. Although the resin at the top of the canister looks good, you can bet that inside the canister (out of sight), there will be a channel of spent resin that the water is flowing through. This effect is called channelling. Just make sure filters are full of water before you apply water pressure from the R.O. and all should be good.

In our experience channeling has little to do with the presence of air trapped in the housing.

Russ

[Buckeye Field Supply]

Are you sure that the yellow line in your photo is the good R.O. and not the effluent that should go to waste.
Yes

[Buckeye Field Supply]

Folks - here's and easy way to remember what cames out which port on an RO membrane housing. Purified water (a.k.a. "permeate") comes out of the center stem of the RO membrane. Waste water (a.k.a. "concentrate") comes out of the end of the body of the element:


http://i224.photobucket.com/albums/dd293/BuckeyeFS/MembraneHousingCutaway-1.jpg

Russ

[Garf]

In our experience channeling has little to do with the presence of trapped air.

Russ

You must get people asking you about problems related to AKANDOs all the time. In your reply do you mean that the flow through the D.I. is channelling but has nothing to do with the air, or channelling is not occurring and some other fault is causing his new resin not to process correctly.

[Buckeye Field Supply]

The presence of trapped air in the housing (outside the axial flow DI cartridge) is unrelated to channeling that may or may not occur...

[Garf]

The presence of trapped air in the housing (outside the axial flow DI cartridge) is unrelated to channeling that may or may not occur...

Agreed, it is the air inside the cartridge where the problem lies. However I think the best way to ensure that the air in the cartridge is released, is to make sure that the outer chamber is full without a pressure applied.

[Buckeye Field Supply]

The other thing is that the resin in the cartridge needs to be packed VERY tightly. If it isn't, the bed will fluidize, and the anion and cation beads will separate by specific gravity.

[Garf]

Floyd - you do like your valves, don't you. You out do me by a factor of ten. Another thing, how do you get to use so much space. I would never get away with that. All mine fits into a small cupboard in the kitchen, look;
2033
sorry about photo. Its been affected somewhat by the light from the kitchen window.

[Ace25]

LOL, my filter fits in a rubbermaid container and sits on top of my refrigerator when I am not using it. I have no room at all to mount a RO/DI filter anywhere in my place.

http://farm8.staticflickr.com/7194/7080561025_31dc03d6db_n.jpg

[Floyd R Turbo]

http://i611.photobucket.com/albums/tt191/FloydRTurbo/2012%20Miscellaneous/RODI%20System/DSC00779.jpg

You can see my DI canister in the above pic is not tightly packed, and the bead separate but seemingly only when they are used up, and then they sink to the bottom. I TDS still zero and beads about 2/3 exhausted. So I guess my question is how is it a problem if the bed fluidizes like this?

[Garf]

LOL, my filter fits in a rubbermaid container and sits on top of my refrigerator when I am not using it. I have no room at all to mount a RO/DI filter anywhere in my place.

http://farm8.staticflickr.com/7194/7080561025_31dc03d6db_n.jpg

In all the photos I've looked at from the U.S., I can't see one pressure relief valve (the red button on my chamber). This simple valve aids greatly in charging the chamber with water slowly when the canisters are changed. Is this a "standard non feature" in the U.S.? All chambers I have seen in the U.K. have a valve. This includes R.O. Pre filters and add on D.I. units. Perhaps I need my eyes tested.

[Buckeye Field Supply]

http://i611.photobucket.com/albums/tt191/FloydRTurbo/2012 Miscellaneous/RODI System/DSC00779.jpg

You can see my DI canister in the above pic is not tightly packed, and the bead separate but seemingly only when they are used up, and then they sink to the bottom. I TDS still zero and beads about 2/3 exhausted. So I guess my question is how is it a problem if the bed fluidizes like this?

Sounds like the bed hasn't fluidized - I can't really tell from the pic.

You'll get better treatment from a mixed bed than from an equivalent volume of separate bed resins. So its not uncommon for a person to read 3 or 4 ppm once the beads have separated - but then to be back down at zero once the beads are remixed.

Russ

[Buckeye Field Supply]

The housings with pressure releif valves are readily available, but are seldom used...

[akando]

Alright. I repacked both DI cartridges. They only took about a table spoon more. Out of the RO membrane I am reading 6 TDS. Out of the first DI I am reading 22 and after the second, 18. What's up with that? I'm letting it make 5 gallons and I'll retest.

[Garf]

Alright. I repacked both DI cartridges. They only took about a table spoon more. Out of the RO membrane I am reading 6 TDS. Out of the first DI I am reading 22 and after the second, 18. What's up with that? I'm letting it make 5 gallons and I'll retest.

What the !! Did you fill the chamber with water before connecting the R.O. line. If so, you didn't use tap water did you. If you didn't pre fill then I would disconnect and pre fill with R.O., then reconnect and test aqain.

[akando]

I prefilled with the extra water I had already filtered. It has a tDS of 9.

[Buckeye Field Supply]

Often when we get customers calling in with DI performance issues, it turns out to be mis-measurement. Collecting samples in a dirty vessel, bad TDS meter, mis-aligned probes on inline meters, measureing samples too soon after the system starts, etc. Other common goofs include using resin that has dried, been packaged poorly or stored for a long time, getting poor quality resin from cut-rate vendors, or installing DI cartridges upside down.

That's where I'd start here.

If you'd rather talk through this feel free to give us a call when you're in front of the system any time before 7 PM eastern time today, or between 8 and 8 tomorrow.

Russ
513-312-2343

[Garf]

Akando - the testing vessel must be cleaned well. Use lots of RO/DI. to rinse of the soap residues. Re-test. I think we've just about covered everything else mentioned by Russ. If this doesn't work, I would do as he sais and give him a call tomorrow.

[Floyd R Turbo]

I can't see how it's the collection container if he tests the RO and gets lower than the DI with the same collection vessel.

[Buckeye Field Supply]

Are we sure he used the same container? The variables in these sorts of situations go on and on - that's why I suggested he give us a call. We can get more accomplished in a 5 minute phone call that we can in 5 pages of posts...

[Garf]

Are we sure he used the same container? The variables in these sorts of situations go on and on - that's why I suggested he give us a call. We can get more accomplished in a 5 minute phone call that we can in 5 pages of posts...

Not as much fun though. Hope that you let us know what the outcome is.

[Garf]

Akando -did you find out what was going on?

[Floyd R Turbo]

That is opposite of what I experience with DI that has been sitting for a few days, it is always way higher than tap water TDS until the water that is in the DI canister gets flushed out. On a home unit, it isn't that much, but it is a short term spike, but still I think that really reduces a secondary DI filter if placed in line, just a waste of DI from my experience. I get much more life just using a single canister than using dual.

On a DI only canister that is 4' tall, there is A LOT of water sitting in there stagnant which is why I see 1500 TDS for up to 5 minutes running the faucet on full open. If the DI canister didn't spill bad stuff into the water, then I shouldn't see much higher than tap TDS, but I see way higher and the company that replaces the DI bottles even said that is how DI works and needs to be flushed daily or else the water coming out will be much worse than tap water. I was told the only way to avoid the issue is to drain the water out of the DI after each use, but that is not a realistic solution IMO.

quote I found:

Ace, just wanted to report to you that I did not experience this effect of high TDS built up in the DI canister. I let my RO/DI system set for at least a week. Then I calibrated my TDS meter. I ran out about 1 gallon through my RO and watched the TDS drop down to about 8ppm. For reference, I'm running 3 prefilters and a 150 GPD membrane, but my water pressure is way low so it only produces about 50 GPD. After it appeared to be at the minimum reading, I engaged my DI and kept the meter in the cup that was collecting the effluent, letting it fill and then pouring most of it out to keep the water changing often enough to see if there was any spike at all. I actually saw nothing but zero the whole time, and I sat there for 5 minutes watching it. Zero the whole time.

[Ace25]

Good to know it doesn't seem to be a wide spread problem. I am wondering how much my location is playing into that. My work location where I experience the issue and my home are in the same town, and has A LOT of farm pestiside/fertilzer run off, so much you can actually taste it in the water, then certain times of the year the water coming out of the faucet smells like a swimming pool because so much chloramines are dumped into the water. I made the mistake of trying to make water during one of those weeks and I ruined every single filter and membrane on my RO/DI setup, and I just bought all new filters 2 weeks prior. Good to know it seems like a localized problem, but having seen it happen to multiple people in the town using many different types of RO/DI filters, I don't think it is just me. Next time I visit that work site I will take a video showing it because it really is so high it is almost unbelivable until you see it with your own eyes. Seriously, brand new 4' DI canister, used for 10 gallons then sit for 24 hours, come back the next day it is always 1300-1500 TDS for up to 5 minutes running the faucet on full. Then it drops down quickly to the point it goes from 1300 down to 0 between minute 5 and 6, which seems to be how long it takes to flush a 4' DI canister. Can anyone else come up with an explanation to what I see? DI canister, no other filter, tap water is 500+, run water through DI until it hits 0, then let the water sit for 24 hours and come back and turn it on and the TDS coming out is almost 3x higher than tap. I can't think of any other reason other than the DI is causing it because there is no other filter in place at my work.

Did you take off the DI canister and dump the water into a testing container? Not that the method you did would negate the test, if you had the extreme issue I seem to have you would have had TDS in the hundreds for around 30 seconds with the filter running, but when you test the stagnent water in the DI canister it seems to be quite a bit higher.

[Floyd R Turbo]

no, I just let the effluent from the RO push through the DI chamber. I would expect if there was any stagnant water pushing through the DI chamber that would have a spike in TDS, if would have been within the first about 2 cups of water. My resin is about 3/4 used in the chamber, so the beads are brown and separated as the bottom, and blue at the top. This is the "Nuclear color changing resin" from BRS.