RODI problems...

[ColoReefer970]

Hi,

So a couple weeks ago I noticed the TDS meter on my RO system start it's creep up... figured its time to replace things. So I do. Now I can't get below 20 to save my life (on 2 different meters) and I've tried everything I can think of.

It's got the prefilters and a mixed bed of the standard color changing stuff.

I've taken it all the way apart and inspected everything and put it back together multiple times... i put a new membrane in. .I've repacked my resin cartridge like a dozen times in case of channeling....still 20 TDS...

I'm pulling out my hair here...

The water coming in is like 130 tds...
The water coming out is 20...
It used to come out at like 1...

I feel like the membrane solo should get max 10.... the DI should pick up the rest... worst case pick up everything and exhaust faster...

But it's not doing that and I'm running out of ideas...anyone got any?

Please feel free to assume I'm a complete moron and may be missing the most basic thing...i certainly feel like one, and won't hold it against you!

(It feels like an emergency when the gap filler is daily 40 minute round trips for a 5g jug)

 

[Flippers4pups]

Do you have any idea of the pressure going to the unit is?

 

[ColoReefer970]

Negative...but it is probably a little high... it's a long run and sometimes you get a little over pressure when you turn the faucet nearby on... i always vent it before turning the RO spigot on. . RO pressure is always in the "operating range"

 

[Flippers4pups]

Knowing what your incoming pressure is, is very important. Incoming pressure should be around 65 psi.

Do you know how old the membrane is?

 

[ColoReefer970]

Brand new membrane and resin
2 week old pre filters

I'm just trying to understand what's going on here... perhaps over pressuring the membrane is rushing things through the resin? And neither of them are doing what they're sposta?

Never had a problem for 5 years until this latest change

 

[Flippers4pups]

Brand new membrane and resin
2 week old pre filters

I'm just trying to understand what's going on here... perhaps over pressuring the membrane is rushing things through the resin? And neither of them are doing what they're sposta?

Never had a problem for 5 years until this latest change

Maybe the membrane isn't seated right.

 

[Flippers4pups]

If a new membrane was put in backwards, I believe it would bypass.

Could be the reason for DI being exhausted so quickly. Does the DI exhaust quickly? Simple mistake on inserting the membrane could cause high TDS to reach the DI chamber.

https://www.bulkreefsupply.com/instructions/article/changing-your-reverse-osmosis-membrane

 

[rkpetersen]

Have you checked the TDS of the water right after the membrane and before the DI resin? With your incoming TDS and a high quality correctly installed new membrane, I would expect it to be around 3.

 

[ColoReefer970]

Definitely installed the membrane the right way putting it upside down was the first thing I figured I was dumb enough to do...

I haven't checked TDS after each stage yet... that's a good idea... unfortunately I can't get to that until morning...

With regards to DI exhaustion.... it was more exhausted on the bottom before I changed it, but its all fresh new now

 

[vetteguy53081]

You could apply a shut off valve to line to unit and reduce a little and see if it changes RO behavior as it sounds like also too much pressure.

 

[Rattzreef]

how long did you flush the new membrane? If I recall, they recommend a flushing out period correct? If you just recently changed it and haven't properly flushed it for the allotted time recommended it could be the issue.. I'd suggest getting a pressure gauge, also as soon as allowed to keep track of it.

 

[ColoReefer970]

They say flush for an hour... it's gone way longer than that.... still 20 TDS ....

I'll tear it apart again in the morning and see where TDS is between the membrane and the resin....

Otherwise I'm looking at a bunch of pressure regulating stuff...? in which case the question becomes.... how best to modify the standard 3 stage from BRS to handle this nonsense...

I appreciate anyone that can throw in a "don't forget x" cuz it'll be the end of the week assuming stuff ships tomorrow...

I'm still confused...i mean I've replaced everything before with no problems...i really feel like it should work but... no...

Thanks again for the inputs...

 

[KStatefan]

Why do you think to much pressure is the problem?

A filmtech 75 gallon per day membrane has a max operating pressure of 300 psi.

 

[pwilliaml]

Check your waste water to product water ratio. If it's not close to 3:1, you could have a problem with your restrictor valve or your membrane housing may have developed a crack in it somewhere. If you've never changed out your restrictor valve, you may want to consider doing that. They are just a small plastic orifice and over time they wear or get clogged with waste water and can cause some problems with your unit. They actually recommend you replace the restrictor at the same time as your membrane. First test though is your waste to product water ratio. If you have a 75 GPD membrane it should be pretty close to 3:1, 3 parts waste to 1 part product. If that's good, try pulling your membrane out of the membrane housing and inspect the very bottom of it with a flashlight for cracks. After that, if your unit is a little older, I suggest replacing the tubes connecting everything and taking apart your auto shut-off valve and cleaning that. First things first though, check your waste to product water ratio. Les us know what you get. High pressure makes your RO unit work better by the way. Virtually no adverse effects until you get over 100 psi.

 

[pwilliaml]

Again, stop with the pressure talk. Your unit will start leaking and such when pressure gets too high before you would see the adverse affects on TDS. Another thing, where is your unit reading TDS, after the membrane, or after the resin cartridge? If you're not burning through resin, your TDS meter may just be out of calibration. If you have a dual TDS, you don't need to measure your inlet water as it rarely changes, and once you know it, who cares what it is. You want to monitor the performance of your unit, so standard practice is to monitor your membrane outlet and your resin outlet so you know when it's time to change the resin and when it's time to change the membrane. you may want to try using the other sensor on your TDS meter to read your TDS to see if the other one is reading wrong. How much water have you made with the new resin? Is it color changing and has a bunch of it turned brown really fast? If not, again, might be a faulty TDS meter. Hope this helps. Let us know what you find out.

 

[DLHDesign]

It's an unlikely problem, but has the temperature in your area changed recently (gotten colder, most likely)? If you've been running the system for years and not seen this issue, it is (again) unlikely to be a temperature issue, but that's something that's easy to check, at least.

It's possible your new membrane is faulty. Do you still have your old membrane? If so, might want to try reinstalling it and re-testing it. If you get a result similar to what you were getting, then it would at least give you confidence that things are likely being installed correctly.

Did you go from a 75GPD membrane to a different rated membrane, by chance (100GPD or higher)?

You mention that is has the pre-filters. What, specifically, does this entail? Sediment and carbon? If so; where those changed out at the same time? Did those (or the carbon, at least) get flushed before being hooked inline with the membrane?

 

[ColoReefer970]

carbon and sediment, yes flushed...

I've tested against the old filter and a second new filter and all go the same way. .

It did just get noticeably colder... we get 40 degree night's lately instead of 70... what's temp affect?

Forgetting about pressure...thx

I've run at least a dozen hours through the new resin and it still looks new...

I've got multiple TDS meters for lots of things... they all say its 20... I'll get at the post membrane TDS and the ratio shortly

Hell I'll check all the little fittings for buildup too..

 

[chipmunkofdoom2]

Check the TDS after the membrane but before the DI. Divide that number by your tap water TDS. If the number is bigger than 0.05, the problem is your membrane. If the number is 0.05 or lower, the problem is your DI resin. It's possible the problem could be both, but it's more likely the problem is one or the other.

Also, replacing all of your filters when the final TDS rises is not an efficient way to manage your RO system. The only thing final TDS tells you is that your DI resin is depleted. It tells you absolutely nothing about the rest of the parts of your system. The prefilters need to be replaced every 6 months on a schedule (or as testing dictates), regardless of what your final TDS is. The membrane similarly needs to be replaced when the rejection rate (post-RO TDS divided by tap water TDS) is greater than 0.05. Your final TDS tells you nothing about how efficiently your membrane is performing.

 

[chipmunkofdoom2]

Also you mention you've repacked your DI resin several times? Have you added more resin each time you re-packed? You really can't repack a DI resin cartridge without adding more resin. If you didn't add more resin, it's possible that repacking did nothing for channeling.

 

[KStatefan]

carbon and sediment, yes flushed...

I've tested against the old filter and a second new filter and all go the same way. .

It did just get noticeably colder... we get 40 degree night's lately instead of 70... what's temp affect?

Forgetting about pressure...thx

I've run at least a dozen hours through the new resin and it still looks new...

I've got multiple TDS meters for lots of things... they all say its 20... I'll get at the post membrane TDS and the ratio shortly

Hell I'll check all the little fittings for buildup too..

Water temperature does not effect it much just reduces the output.

I was incorrect on the max psi in my previous post. Max operating pressure is 150 psi.