Rodi trouble

[Wiz]

Okay rodi Specialists, I just bought a new membrane after buying all new filters a month or two ago. When I got to my lfs I asked for the 75 gallon per day membrane and they only had a hundred but the owner swore up and down that the hundred and seventy-five were interchangeable. I just wouldn't pump a hundred the restrictor would keep it at 75. When I got home and compared the two membranes the hundred one was a quarter inch or less bigger than the one that I had. He swore it was interchangeable and it was not that big of a difference so I tried it in the housing and it fit fine closed water tight does not leak. The water goes through slowly but okay but I am getting a reading of 1 PPM still. Even after running the filters for more than a day. I pulled off the hose before the DI resin and it is feeding at 16. That's with three new filters in the canisters and a brand new membrane. I feel like that's high. Do you think the 100 membrane is somehow not working properly maybe because it's slightly too large?

 

[Crabs McJones]

Okay rodi Specialists, I just bought a new membrane after buying all new filters a month or two ago. When I got to my lfs I asked for the 75 gallon per day membrane and they only had a hundred but the owner swore up and down that the hundred and seventy-five were interchangeable. I just wouldn't pump a hundred the restrictor would keep it at 75. When I got home and compared the two membranes the hundred one was a quarter inch or less bigger than the one that I had. He swore it was interchangeable and it was not that big of a difference so I tried it in the housing and it fit fine closed water tight does not leak. The water goes through slowly but okay but I am getting a reading of 1 PPM still. Even after running the filters for more than a day. I pulled off the hose before the DI resin and it is feeding at 16. That's with three new filters in the canisters and a brand new membrane. I feel like that's high. Do you think the 100 membrane is somehow not working properly maybe because it's slightly too large?

If you're using a 100gpd membrane but have a 75 gallon per day restrictor that may be contributing to it. When's the last time you changed your di resin? 16 out of your to membrane depended on your source water isn't bad. Your di should be able to polish that off.

 

[Wiz]

I replaced the four canister including the di resin about a month ago it read zero for a few days but then one day shot from 0 in the morning to a little over 54 at night so I assume the membrane was bad. That's when I replaced the membrane. The DIY resin has a 1 or 2 inch section of orange but is still 80% green

 

[K. Steven]

Make sure the DI resin is packed tightly so there is no channeling of high TDS making it into your product water.

 

[Crabs McJones]

I replaced the four canister including the di resin about a month ago it read zero for a few days but then one day shot from 0 in the morning to a little over 54 at night so I assume the membrane was bad. That's when I replaced the membrane. The DIY resin has a 1 or 2 inch section of orange but is still 80% green

I would probably then assume that the 100 gallon per day membrane with a 75 gallon per day restrictor is causing your issue. Do you know what the rate of your restrictor valve? 400ml or 550ml?

 

[Wiz]

will double check when I get home however the lfs pre measures and bags it so it is pretty hard to get wrong.

 

[Wiz]

Not without looking. And I won't be home until tonight. Do you guys think the DIY resin should be able to clean the 16 PPM that is going in out? Some have said yes and some have said no. If yes then I would say the D I might be having an issue because the feed going into the DIY resin is 16 PPM coming out as one.

 

[K. Steven]

will double check when I get home however the lfs pre measures and bags it so it is pretty hard to get wrong.

If you pack your own DI resin into the cartridge, compress it every third of the way up the cartridge as you pack it. I use a beer bottle to firmly compact the resin as I pack.

 

[Crabs McJones]

Not without looking. And I won't be home until tonight. Do you guys think the DIY resin should be able to clean the 16 PPM that is going in out? Some have said yes and some have said no. If yes then I would say the D I might be having an issue because the feed going into the DIY resin is 16 PPM coming out as one.

How is your di cartridge oriented? A picture of it would better help.

 

[Wiz]

Thats it sittin on my basement floor

 

[Crabs McJones]

Thats it sittin on my basement floor

On your flush valve in the last picture, what is the flow rate, I think it says 500

 

[Wiz]

I'm having my wife check right now but it is a BRS 75 gallon a day restricted

 

[Wiz]

Thats it

 

[lyscer]

Thats it

Couple of questions.

1. What is the rejection rate of the membrane?
2. What is the TDS of the RO right out of the membrane after it has been producing RO for at least 15 minutes?
3. What is your tap water TDS?

For the next 2 run your RO unit for 15 minutes or so prior to the test.
4. How much water comes out of the drain/waste line in 60 seconds?
5. How much water comes out of the production line (right after the RO membrane) in 60 seconds?
6. What is the temperature of the water going into the membrane?

My guess is that the imbalance of membrane to restrictor valve is your issue. But this should help us narrow down what to do.

 

[Wiz]

The 75 gallon per day membrane which is what I had previously ran fine with the restrictor at 800. Which apparently is also the size for a 100 gallon. So the restrictor should not have anything to do with it I don't think. The 75 says either 500 or 800. 100 says 800. The restrictor I have is 800.
Everything on the filter is exactly the same as when it ran fine except for the membrane.

 

[Wiz]

Membrane should be 96 to 98%. Water feeding in is a bit over a hundred. The DI resin comes after the membrane. Before the Di read 16. After the DI Reads 2.
I would imagine the temp of the water is cold. It's in my basement. But it is the same as it has been and it did work fine

 

[Wiz]

These readings that I gave you are after it had been running for eight hours

 

[lyscer]

So to determine if your membrane is being as effective as it should be let's assume the following:
{X} Tap TDS: 100ppm
{Y} Membrane Output TDS: 16ppm
[(X - Y) / X] * 100 = [(100 - 16) / 100] = 84% (This is your current rejection rate based on the rough numbers you gave)
This implies that there is definitely a problem with your RO membrane since it isn't performing at 96%. Since it is a new membrane I would guess that it is probably functioning fine so you would need to test the input/output from my question above to determine if it is the flow restrictor causing the issue or if you have a fouled membrane.

 

[Wiz]

I get home pretty late but I will post the results later tonight

 

[Wiz]

Ok so a friend came over for water and i was demonstrating the problem. Its different now.
Input = 158
Before di = 1
After di = 2

Resin has roughly 40% orange at top. 60% green. I dont gethow its coming out higher after resin. Also the membrane seems to be working now. Still cant get 0 though