beatle March 1, 2011 Share March 1, 2011 (edited) My beefy Ocean Reef +1 w/an 8800 booster pump and pre-pump sediment filter just got another upgrade in the form of a second 75gpd Dow membrane. I replaced both membranes when I did the upgrade, and all filters are only about 2 months old, including the resin. Before the dual membrane upgrade, my TDS coming out of the single membrane was originally about 2, but it had started to creep up to 5. I'm not sure if the tap's TDS went up or if the membrane was just getting on in years (it's probably had several thousand gallons through it). When I upgraded, however, TDS was in the low teens, even after flushing the membranes for several minutes. Tap TDS is 250-300. Last night I finally stood up my 55g RO/DI reservoir and made about 40 gallons of water. About halfway through, I noticed the TDS had dropped to 5-6 on the RO, but DI was now 1. Apparently I've blown through the resin this quickly? I'm using Filter Guys' mixed bed resin, FWIW. Edited March 1, 2011 by beatle Link to comment Share on other sites More sharing options...
sportzfish March 1, 2011 Share March 1, 2011 For some reason, I remember reading somewhere that if the rejection rate of the membrane is not high enough, then it would in fact cause rapid depletion of the resin. Link to comment Share on other sites More sharing options...
beatle March 1, 2011 Author Share March 1, 2011 The 75gpd Dow Filmtecs should be >98%. That puts my TDS readings in line with the proper rejection rate now, though it had a pretty bumpy start. Initial TDS was incredibly high. I briefly saw over 100 as it would start up! I typically made water in 5g batches, hopefully the larger reservoir will let me start making them in 40-50g batches and stave off TDS creep. Still bizarre that I blew through a canister of resin in only a couple months. Link to comment Share on other sites More sharing options...
Origami March 1, 2011 Share March 1, 2011 The RO membrane may not be fully seated in the housing. Check it. If the o-ring is not sealing properly, TDS will leak, bypassing the membrane, and will rapidly deplete your DI resin. Link to comment Share on other sites More sharing options...
beatle March 1, 2011 Author Share March 1, 2011 I'll give it a check. I did lube the O-rings at the top and bottom. Link to comment Share on other sites More sharing options...
Origami March 1, 2011 Share March 1, 2011 Make sure that the double o-rings are fully seated inside the housing. They go in first. It will be a tight fit. By the way, did you flush the membrane after installation? You do this by bypassing the DI resin and running the membrane under pressure for a couple of hours to flush the membrane preservatives from the cartridge. Link to comment Share on other sites More sharing options...
Dragon Eye March 2, 2011 Share March 2, 2011 Even in the low teens, a refill should last for a lot of water. How many gallons have you made on that cartridge? Also, think about adding a bypass for the product water to the drain. It takes some time for the membrane to reach its full performance when it is pressurized. You can see the spike on your TDS meter. It can sometimes take a minute or two to go from the tap TDS down to the normal level. Each time you run this through your DI, it uses up more resin than probably dozens of gallons of water at regular operation. On mine, I have a valve to dump the product water, I turn it on and wait a minute or two, then I turn on the valve to the DI and shut off the bypass. The resin lasts much longer. At my last place, incoming TDS was 800-900 so I started finding tricks like that because I was burning through a lot of resin and it was getting expensive. Link to comment Share on other sites More sharing options...
beatle March 2, 2011 Author Share March 2, 2011 I'm really not sure, as I've "let it go" a few times making water in the deep sink overnight. I do have a fast flush valve that bypasses the restrictor. I let it run for 5-10 minutes when I first put the membranes in. I'd never heard of it needing to be run for hours, but maybe that's my issue? Oddly enough, the resin is only half color changed. The bottom half appears different from the top, though TDS is now hovering around 1-2. Link to comment Share on other sites More sharing options...
Origami March 2, 2011 Share March 2, 2011 Flushing it for a few hours (bypassing the DI stage so you don't exhaust your resin early) at the start just clears the membrane preservative that's put there during manufacture to prevent it from drying out and degrading. Link to comment Share on other sites More sharing options...
beatle March 2, 2011 Author Share March 2, 2011 Sounds like we differ on what the "flush" is. I thought it was bypassing the flow restrictor on the waste line, not the DI stage, though I could do that as well. With the restrictor bypassed, all the water flows down the drain and there is no product. Link to comment Share on other sites More sharing options...
FearTheTerps March 2, 2011 Share March 2, 2011 Here's a link to AWI that states how long their DI resin should last, Its not very long at all. Their vertical cartridge will handle about 6800 ppm total, it doesnt take very long to take that up. http://www.airwaterice.com/category/z.2/ Link to comment Share on other sites More sharing options...
DaveS March 2, 2011 Share March 2, 2011 I'm really not sure, as I've "let it go" a few times making water in the deep sink overnight. I do have a fast flush valve that bypasses the restrictor. I let it run for 5-10 minutes when I first put the membranes in. I'd never heard of it needing to be run for hours, but maybe that's my issue? Oddly enough, the resin is only half color changed. The bottom half appears different from the top, though TDS is now hovering around 1-2. If you are using color change as the indicator, that could be part of the problem. The color change occurs much sooner than actual resin depletion. You should use a tds meter to determine true end of life for the resin. Link to comment Share on other sites More sharing options...
beatle March 2, 2011 Author Share March 2, 2011 No, I have a TDS meter. I just found it odd that the color change had not happened evenly across the entire cartridge. Link to comment Share on other sites More sharing options...
FearTheTerps March 2, 2011 Share March 2, 2011 sometimes the water can channel through the resin, which could be a reason for the color not evenly changing. Ive also heard a few people say that the resin will actually go through 2 color changes. It will change some at first, but as it gets used more the color change becomes more apparent. Link to comment Share on other sites More sharing options...
Dragon Eye March 2, 2011 Share March 2, 2011 Sounds like we differ on what the "flush" is. I thought it was bypassing the flow restrictor on the waste line, not the DI stage, though I could do that as well. With the restrictor bypassed, all the water flows down the drain and there is no product. That's a different problem. Once you close the bypass to the restrictor, it will then pressurize and you'll get the spike on the output. Basically, run it normally but dump the product water until your output TDS is down to the normal range. Then turn on the valve to the DI and shut off the valve for dumping the product water. Link to comment Share on other sites More sharing options...
Origami March 2, 2011 Share March 2, 2011 Sounds like we differ on what the "flush" is. I thought it was bypassing the flow restrictor on the waste line, not the DI stage, though I could do that as well. With the restrictor bypassed, all the water flows down the drain and there is no product. That's a "fast flush." In theory, it's used to clear the pressure (input) side of the membrane clear of TDS that are trapped there (by the membrane). It's kind of like cleaning off the lint trap in your dryer: You bypass the flow restrictor, allowing water to pass quickly through the pressure side. Normally, this side is under pressure, and since the output side is at a lower pressure, water seeps through the membrane from the input side, through the membrane, which acts (literally) as a microscopic mechanical filter. When you bypass the flow restrictor, the junk that the filter trapped is flushed out the waste port. This increases the lifespan of the membrane. The flush I'm talking about is to "clean" the membrane of stuff used in manufacturing. Membranes are not supposed to ever be left to dry out. When they dry out, they can't properly re-wet (even under high pressure), and surface area (available for the RO action), efficiency, and output - all interrelated - fall drastically. To keep the membrane from drying out between the time when it's manufactured and the time it's installed, a membrane preservative is used. This preservative is on both sides of the membrane and, from our perspective, is a pollutant. So, the flushing process that I'm talking about is basically a thorough rinse that prepares the membrane for service. And, a two hour flush, for a 75 gpd membrane runs about 7 gallons of water through the output side to rinse out that side of the membrane. Since the output side of the membrane feeds the DI stage, the preservative on that side will pass through that stage (to be cleaned up there) unless you bypass the DI stage. Link to comment Share on other sites More sharing options...
Integral9 March 2, 2011 Share March 2, 2011 No, I have a TDS meter. I just found it odd that the color change had not happened evenly across the entire cartridge. I don't believe both resins have the color changing dye in them, so that could be what you are seeing. But as a fail safe, I'd check the TDS and if your not seeing a drop in TDS after your RO water runs through the DI canister(s), the resin is spent. Link to comment Share on other sites More sharing options...
beatle March 5, 2011 Author Share March 5, 2011 Just an FYI if anyone else has made this mistake, when I filled the resin cartridge, I did not pack it tightly. Sure, it was "full" but it was not packed at all, and there may have even been a significant gap at the top of the cartridge. I just watched the that shows how to properly pack a resin cartridge. I don't think this singlehandedly led to the downfall of my resin, but it's a good tip. Link to comment Share on other sites More sharing options...
Buckeye Field Supply December 2, 2011 Share December 2, 2011 For some reason, I remember reading somewhere that if the rejection rate of the membrane is not high enough, then it would in fact cause rapid depletion of the resin. Right. The more pure the water is that feeds the DI, the longer the DI resin will last. Russ Link to comment Share on other sites More sharing options...
Origami December 3, 2011 Share December 3, 2011 In the event that you're on a well, high CO2 in the source water can also rapidly deplete DI resin as it is small enough that it pretty much passes right through the RO membrane. And, because it's weakly ionized, it's not easily detected using standard conductivity ppm meters. Still, it has an affinity for DI resin as it interacts with water to form carbonic acid, and carbonate and bicarbonate ions. So, if you're a well, with low source water pH, this could be part of the problem. It kind of looks like Buckeye Field Supply is trolling for posts with RODI in the text... even if they're months old. (I just noticed that this thread is now resurrected from many months ago.) Link to comment Share on other sites More sharing options...
YBeNormal December 3, 2011 Share December 3, 2011 "Trolling" seems kind of harsh. True, he is a vendor, but he's offering good advice (even if it is long after the thread has died down) and I haven't seen him pushing any of his products. Link to comment Share on other sites More sharing options...
Origami December 3, 2011 Share December 3, 2011 "Trolling" seems kind of harsh. True, he is a vendor, but he's offering good advice (even if it is long after the thread has died down) and I haven't seen him pushing any of his products. I use trolling as a fishing technique/term. I guess it could be misconstrued. Link to comment Share on other sites More sharing options...
Buckeye Field Supply December 3, 2011 Share December 3, 2011 "Trolling" seems kind of harsh. True, he is a vendor, but he's offering good advice (even if it is long after the thread has died down) and I haven't seen him pushing any of his products. Thnaks! I appreciate the sentiment! Link to comment Share on other sites More sharing options...
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