Reverse osmosis membrane change out

[AllSignsPointToFish]

I use an Aquatic Life RO Buddie system. I have to change out my membrane about once a year, even with routine prefilter changes. Does anyone else have this issue? I can usually tell when it's time for a new membrane because my deionizing resin needs much more frequent changes.

 

[Randy Holmes-Farley Verified Community Expert]

I never had an RO membrane go bad, even after many years, but most often, what people find is they get clogged with deposits.

If you are finding them to become more penetratable (and hence have a lower rejection rate so the DI would get consumed faster), perhaps chlorine is getting through your carbon prefilters and damaging the membrane, putting holes into it.

 

[AllSignsPointToFish]

I never had an RO membrane go bad, even after many years, but most often, what people find is they get clogged with deposits.

If you are finding them to become more penetratable (and hence have a lower rejection rate so the DI would get consumed faster), perhaps chlorine is getting through your carbon prefilters and damaging the membrane, putting holes into it.

With the latest membrane, I actually modded out my RO Buddie for exactly this reason. I retrofitted another carbon filter upstream of the membrane so that the sediment filter is followed by two carbon filters instead of one. I also have another multi-filter housing that I could put into service that can house 2-3 more extra GC and block carbon filters. We'll see if I need to get that extreme.

There must be something wrong with the membrane because the tap water measured a TDS of 281 ppm last night (not great, but not terribly high, either), and my RO exit measured 70-80 ppm TDS (which is why my DI resin was getting exhausted so rapidly.

 

[Buckeye Hydro Verified Sponsor]

If your water is very hard, the membrane can "scale" - that is, hardness scale can deposit inside the element. You'll notice slowed flow of purified RO water as the membrane plugs. This same scale can abrade the membrane and essentially create holes in the membrane that allow more TDS through. Randy's other suggestion is a good one... We reeeeeaaaaaly don't like those RO buddies because of the misapplication of the small filters that system uses as prefilters. If for some reason you really like that configuration, think about dropping down to a 24 gpd or slower membrane.

Russ

 

[Ty Hamatake]

Whay is your water PSI at? If I'm not mistaken, that can have a slight effect on membrane efficiency. Maybe it wouldn't make that much difference anyway...

 

[alton]

My rural water company uses Chloramines, and sometimes I get an overdose since I am so close to the pump station. I change my membrane every year and have for years. I need to buy the chloramine monster from BRS.

 

[AllSignsPointToFish]

I don't think scale is the problem as I don't see a reduction in capacity.

The water pressure I have is pathetic. There is a new water tower coming online, but it has not yet been commissioned. In fact, the water pressure I have is so bad that I can't even flush my outboard while running without getting a temperature alarm after five minutes or so.

I have a three-stage filter that I think I'm going to put into service. It's from a previous RO unit, and it has a sediment filter and two carbon block filters. If I install this upstream of my RO Buddie, I think it would help add additional prefiltration capability.

 

[Paul B]

My last one lasted 9 years.

 

[Buckeye Hydro Verified Sponsor]

I have a three-stage filter that I think I'm going to put into service. It's from a previous RO unit, and it has a sediment filter and two carbon block filters. If I install this upstream of my RO Buddie, I think it would help add additional prefiltration capability.

Yes - if you have some full size filter housings, just use them and get rid of those ridiculous, misapplied prefilters on the RO buddy. You'll be $ ahead and get better treatment. Also sounds like a booster pump might do wonders for you.

Out of curiosity, how did you tap into your plumbing to get water to the system? Hopefully not a self piercing saddle. If so, that may be at least part of the problem.

Russ

 

[AllSignsPointToFish]

Yes - if you have some full size filter housings, just use them and get rid of those ridiculous, misapplied prefilters on the RO buddy. You'll be $ ahead and get better treatment. Also sounds like a booster pump might do wonders for you.

Out of curiosity, how did you tap into your plumbing to get water to the system? Hopefully not a self piercing saddle. If so, that may be at least part of the problem.

Russ

No, I ran a tee with a separate valve (I don't trust saddle valves in pressurized service). Out of curiosity, why would you suggest a self-piercing saddle could contribute to the problem?

 

[AllSignsPointToFish]

I've also instituted TDS monitoring into and out of the deionizing cartridge.

 

[Buckeye Hydro Verified Sponsor]

Out of curiosity, why would you suggest a self-piercing saddle could contribute to the problem?

The small diameter holes they make build up scale around the edge, and over time, the hole gets smaller and smaller, and cuts off flow, and thereby, dynamic pressure.

Russ

 

[AllSignsPointToFish]

The small diameter holes they make build up scale around the edge, and over time, the hole gets smaller and smaller, and cuts off flow, and thereby, dynamic pressure.

Russ

Okay, gotcha. I thought you were implying that saddle valves reduce the effectiveness of the RO membrane! LOL

Yes, reduced differential pressure would reduce output, but I don't see that as too much of an issue right now as quantity produced is acceptable. Rather, it seems that the quality of the RO output decreases with time which leads me to conclude there is something degrading membrane performance.

 

[Buckeye Hydro Verified Sponsor]

Loss of pressure can cause a substantial decrease in rejection. Be happy to help you troubleshoot if you'd like - feel free to give us a call when you are in front of your system.

Russ

 

[AllSignsPointToFish]

Loss of pressure can cause a substantial decrease in rejection. Be happy to help you troubleshoot if you'd like - feel free to give us a call when you are in front of your system.

Russ

Loss of pressure would also manifest itself in slower production rates as well (assuming no internal bypass in the RO housing). The volume produced is pretty much where it needs to be, so I would assume I have sufficient pressure available. However, I can see that a booster pump could potentially help if I have lower-than-normal supply pressure, but I would prioritize the need to get my sediment/carbon filtration sorted out as higher at this point.

Appreciate the troubleshooting offer!