TDS our of Membrane High

[maginter]

Hi -

Looking for someone else that has had this issue. I have a 7 Stage RODI system - 100GPD with BRS Water Saver that I have been trying to get better performance from. The RODI was originally a 75 GPD that I just swapped the membrane to a 100GPD. I got a Smart Buddie to boost the pressure, and it did, from 45psi to over 100psi. I was reading TDS out of the main membrane at 80 and out of the Water saver at 125 with a combined output of 95 - 100. Needles to say, I was burning through Anion Resin like crazy. So I have removed the booster and added a 550ml Restrictor. With this configuration the pressure is 60psi and I get 17 out of the main and 19 out of the water saver. for a total of 17-18. Source TDS is 365.

In this confirmation, the output of each membrane seems still to high. I was expecting something like a TDS of 10 for both. Both membranes are brand new and they have been flushed and run for a few hours. Once question I do have is it possible for the membrane canisters to become deformed or wear out with the higher pressure? My assumption is that I am now getting waste water blow out into my clean water.

I would assume that the answer is no, based on their construction, but trying to investigate the obvious. I also wonder if a newer canister will have a tighter interference with the O-rings on the end of the membrane?

Again, looking for input from people that have had this experience.....

TIA.....

 

[MNFish]

What is you tds at source?

 

[maginter]

Sorry, the one piece of information I forgot.... 365

 

[DeepintheReef]

That seems about correct. My TDS out of the tap is 375 and the TDS out of the membrane runs 15-20 depending on long it’s been in there. That’s about 95% rejection rate

 

[NowGlazeIT]

Hi -

Looking for someone else that has had this issue. I have a 7 Stage RODI system - 100GPD with BRS Water Saver that I have been trying to get better performance from. The RODI was originally a 75 GPD that I just swapped the membrane to a 100GPD. I got a Smart Buddie to boost the pressure, and it did, from 45psi to over 100psi. I was reading TDS out of the main membrane at 80 and out of the Water saver at 125 with a combined output of 95 - 100. Needles to say, I was burning through Anion Resin like crazy. So I have removed the booster and added a 550ml Restrictor. With this configuration the pressure is 60psi and I get 17 out of the main and 19 out of the water saver. for a total of 17-18. Source TDS is 365.

In this confirmation, the output of each membrane seems still to high. I was expecting something like a TDS of 10 for both. Both membranes are brand new and they have been flushed and run for a few hours. Once question I do have is it possible for the membrane canisters to become deformed or wear out with the higher pressure? My assumption is that I am now getting waste water blow out into my clean water.

I would assume that the answer is no, based on their construction, but trying to investigate the obvious. I also wonder if a newer canister will have a tighter interference with the O-rings on the end of the membrane?

Again, looking for input from people that have had this experience.....

TIA.....

To answer your question about deformed housing from high pressure, I don’t think 100psi is enough to break or bend the housing. But there is a rubber seal around the membranes that could. Once I had a high tds issue and found this rubber seal to be folded over on one side.

The fact that both membranes are effected, leads me to believe there may be a problem with the way the lines are installed.

 

[maginter]

To answer your question about deformed housing from high pressure, I don’t think 100psi is enough to break or bend the housing. But there is a rubber seal around the membranes that could. Once I had a high tds issue and found this rubber seal to be folded over on one side.

The fact that both membranes are effected, leads me to believe there may be a problem with the way the lines are installed.

All seals were check and in place. Lines are plumbed per BRS instructions. Now, one other thing.... The TDS Meter that I am using at the back side of the membranes is a HM Digital DM-1 TDS Meter, that came with the original unit 4 years ago. I thought that the probes could be going bad, but I have the HM Digital TDS Meter 3 probes, after the carbon block, at the combined lines at the back of the membranes and after the DI. since the meter at the combined lines after the membrane is reading what I would consider to be a proper value, based on the individual readings. I am taking the probes out of the equation.

 

[MNFish]

I agree that 95% is good, I am a bit stumped if you increased pressure and messed up something then when pressure decreased I would assume you would not get as good of a reduction rate. I am assuming you are using a DOW membrane?

 

[maginter]

I agree that 95% is good, I am a bit stumped if you increased pressure and messed up something then when pressure decreased I would assume you would not get as good of a reduction rate. I am assuming you are using a DOW membrane?

Same here, and that is why I changed out the membranes. Yes, Dow from BRS