Help TDS through the roof and so is my DI resin budget!

[Bradley Keck]

I would not run any thing thru the DI resin until you get this fixed. No sense wasting DI resin.

What do you mean "new regulator"?

Agreed. I'm going to have to though if I cannot get it fixed soon. Going to need to do a WC in a week. What I meant by regulator is the flow restrictor/flush valve.

 

[Bradley Keck]

Ok, thank you for the clarification.
In post 73 @pwilliaml had some good information for you. We need to get the rejection rate closer to the 3:1 ratio he listed with information from BRS.
I also agree with Kstatefan that you should disconnect the DI portion until you get this solved.
Try putting the new restrictor back in and see if you can lower the rejection rate.

Let us know how it goes.

Thank You! So, these readings are with the new restrictor on. The old restrictor did not hiss and my TDS went from 120's to 190's. also my waste to product was not even measurable. I filled one cup with RODI and barely had filled the bottom of one cup with waste water when the old restrictor was on there. Just crazy!

 

[TMB]

Just a thought for something else you could try:
If the 7.5:1 was with the new housing, newest membrane, and new restrictor, try letting the unit run for a few hours.
Disconnect the DI, run lines outside, or into a drain line somewhere, and just let it run.
I've heard that sometimes the entire membrane may take a while to become wet, and working.
Come back every so often and check the TDS out out, and the rejection ratio. you're looking to get it down to 3:1.

 

[Bradley Keck]

Just a thought for something else you could try:
If the 7.5:1 was with the new housing, newest membrane, and new restrictor, try letting the unit run for a few hours.
Disconnect the DI, run lines outside, or into a drain line somewhere, and just let it run.
I've heard that sometimes the entire membrane may take a while to become wet, and working.
Come back every so often and check the TDS out out, and the rejection ratio. you're looking to get it down to 3:1.

Good idea. I will give it a try this evening and see what happens. The longest I have left on with all the new parts was an hour. The TDS were creeping up at line one so I just shut it down. But, that was so I wasn't going through DI resin. I can easily set it up to what your describing. Thank You! Maybe that gets the membrane working. I am starting to think that maybe it is something with this new membrane. Whether it is shot or not primed enough yet. To this point, I have run it probably total of only 3 hours and never more than an hour at any given time. When this system worked like it should for the first 160gallons of RODI made, I never read more than 20TDS, but that was before everything started to go wrong.

 

[TMB]

I have 1 more question, how to you turn this system on and off? are you turning the water source on/off? or do you have a manual shut off valve on the product line after the DI?

 

[Bradley Keck]

I have 1 more question, how to you turn this system on and off? are you turning the water source on/off? or do you have a manual shut off valve on the product line after the DI?

I have a split attached to my hose spigot that has ball valves on them. The source line is attached to one of these. I open the valve and then turn the water spigot on. Only thing after the DI is the float valve in the RODI storage container. That is triggered when it reaches 50g.

 

[TMB]

2 suggestions I have to help your system run better, point 2 will help you for the future more than it will now.
You should hook up your RODI system so that there is constant water pressure going into it and leave it that way. The membrane is not meant to dry out, it will ruin it.
After you run the system for several hours, leave it pressurized, that will also help with making sure the membrane is thoroughly soaked.
So you will want to hook it all back up, and use a shut off (below).
Also, when you do get this running you will want to add a manual shut off valve before the DI stage like this

The reason is that when the float valve shuts off the flow, something called TDS creep happens. This is when the two sides of the membrane are at equal pressure, the TDS also equalizes on both sides of the membrane.
What will happen next is evaporation (or water use) will open the float valve and allow the RO to run, and it will send source water TDS to your DI stage. This is actually going to happen every time you turn on the RO system (unless you flush the first few minutes to waste).
The constant on/off of the RO, coupled with TDS creep, will exhaust your DI super fast, like in a couple weeks. long runs of making water is much better for your system, making small amounts is hard on everything in the RODI system. Remember that leaving the system pressurized is better for the membrane, so this is something you will grapple with at some point.

 

[Bradley Keck]

My system has been on for an hour running through the sediment filter, dual carbon blocks and membrane only. Checked my TDS and they read 68. That is the lowest reading I have seen in a while. I watched it for about 5 min. I noticed it stayed mostly at 68, but it jumped to 22 for about 5 seconds, then went to 70 and then back down to 68. I'll keep checking and leave it on for a couple more hours. Hoping this works!

 

[TMB]

My system has been on for an hour running through the sediment filter, dual carbon blocks and membrane only. Checked my TDS and they read 68. That is the lowest reading I have seen in a while. I watched it for about 5 min. I noticed it stayed mostly at 68, but it jumped to 22 for about 5 seconds, then went to 70 and then back down to 68. I'll keep checking and leave it on for a couple more hours. Hoping this works!

Can you tell me the rejection ratio?

 

[Bradley Keck]

2 suggestions I have to help your system run better, point 2 will help you for the future more than it will now.
You should hook up your RODI system so that there is constant water pressure going into it and leave it that way. The membrane is not meant to dry out, it will ruin it.
After you run the system for several hours, leave it pressurized, that will also help with making sure the membrane is thoroughly soaked.
So you will want to hook it all back up, and use a shut off (below).
Also, when you do get this running you will want to add a manual shut off valve before the DI stage like this

The reason is that when the float valve shuts off the flow, something called TDS creep happens. This is when the two sides of the membrane are at equal pressure, the TDS also equalizes on both sides of the membrane.
What will happen next is evaporation (or water use) will open the float valve and allow the RO to run, and it will send source water TDS to your DI stage. This is actually going to happen every time you turn on the RO system (unless you flush the first few minutes to waste).
The constant on/off of the RO, coupled with TDS creep, will exhaust your DI super fast, like in a couple weeks. long runs of making water is much better for your system, making small amounts is hard on everything in the RODI system. Remember that leaving the system pressurized is better for the membrane, so this is something you will grapple with at some point.

Thank You. the kit came with a shut off valve I can easily hook into the source line. No problem leaving the spigot on and the valve open. I had no idea I needed a shut off before the DI! I did make the mistake with the OLD membrane of not leaving it pressurized. I always flush the membrane for 5-10 min before and after use and I use to just leave the flush valve open and shut off the source water. I had someone else tell me that this was not good and would dry out the membrane. I made sure to not do this with the new one. I did make 40-50gallons at a time before I started to notice the problem and will make sure to keep doing it that way once I get this fixed. Wow, there is a lot about RODI systems they do not tell you! It's just like hook it up and let it run!

 

[Bradley Keck]

Can you tell me the rejection ratio?

I will measure it as soon as I take my girls to swim practice.

 

[TMB]

I agree that there is little information shared about the "best" use of an RO system. I'm lucky enough to live a few miles from one of the leading RODI manufactures in the Aquarium hobby. They taught me a lot when I was learning.

 

[TMB]

Thank You. the kit came with a shut off valve I can easily hook into the source line. No problem leaving the spigot on and the valve open. I had no idea I needed a shut off before the DI! I did make the mistake with the OLD membrane of not leaving it pressurized. I always flush the membrane for 5-10 min before and after use and I use to just leave the flush valve open and shut off the source water. I had someone else tell me that this was not good and would dry out the membrane. I made sure to not do this with the new one. I did make 40-50gallons at a time before I started to notice the problem and will make sure to keep doing it that way once I get this fixed. Wow, there is a lot about RODI systems they do not tell you! It's just like hook it up and let it run!

Yes, leave the source on all the time, and install the shut off between the membrane and the DI stage.
When you close the manual valve it will cause the auto-shut-off to close, and shut off the source water, and leave the membrane pressurized.

 

[Bradley Keck]

Yes, leave the source on all the time, and install the shut off between the membrane and the DI stage.
When you close the manual valve it will cause the auto-shut-off to close, and shut off the source water, and leave the membrane pressurized.

OK. So my waste/product ratio has gone to 11/1. I filled exactly 11 cups of water for 1 cup of RO. The TDS stayed at 72 The system had been running for 3 hours when the measurements were taken. Out of curiosity, since I had not measured TDS as low as 72, I hooked the system back up to the DI and the TDS at line 1 went up to 190. What the?

 

[Tony Elenbaas]

I had a similar issue with high TDS out of the RO, the higher the pressure in the system the higher the tds out. This could be what you are seeing by adding back pressure of the DI. My RO housing had a crack that allowed the waste water to leak into the RO output. I replaced the housing and worked as usual. It sounds like you have a leak either it's the housing or membrane.

 

[TMB]

OK. So my waste/product ratio has gone to 11/1. I filled exactly 11 cups of water for 1 cup of RO. The TDS stayed at 72 The system had been running for 3 hours when the measurements were taken. Out of curiosity, since I had not measured TDS as low as 72, I hooked the system back up to the DI and the TDS at line 1 went up to 190. What the?

When you say line one, do you mean out of the membrane and into the DI stage?

Here is what I would do next, I would use what ever I had laying around to restrict the waste water line more.
Set it up again to run through the membrane only and put that shut off valve on the waste water line and partially close it until you get a 1:3 ratio. I know this is not the right way to do it, and not meant to be a long term solution, I just want to see if you start getting better rejection numbers with the proper ratio.

Can you take some more pics of your system and post them here? It would be helpful to see more of it from other angles and a shot showing the whole RODI system.

 

[pwilliaml]

Hmmm, interesting stuff here. From experience and understanding how RO membranes work, when you add your resin canisters to the outlet of the RO unit, you create some backpressure that will reduce the efficiency of a membrane and increase your waste water to product water ratio (more waste water), but yours is quite excessive. It's starting to sound like you have a clog in your product lines as well or quite possibly in your auto shut off valve too. It may be worth taking all the lines off of your RO unit and inspecting them for clogs, and possibly replacing them as RO lines are cheap. Quick test would be to blow air through them with your mouth. It should be super easy. As for the auto shut off valve, some of them can be dismantled and inspected. I haven't used one for a long time as I've made mine all electronic. TMB is right about keeping your unit pressurized. I do the same to mine. So in summary, you have a new housing, new flush valve / restrictor, kind of new RO membrane, and the only other parts left to replace are the lines and the auto shutoff valve. I would strongly consider inspecting / replacing those and then run the unit with no resin canisters and see if your waste / product water ratio comes closer to 3:1. You can also temporarily remove the auto shut off valve and just connect the product line to product outlet of the membrane, and the restrictor / flushing valve to the waste outlet of the membrane (preferably with new tubing). That will take everything out of the picture and test just your membrane and membrane housing and let you know if it is the problem, or if it's your lines / auto shut off that is the issue. I hope that helps. Hope you have time to play mad scientist for a little while as this will get you to the problem. When I get home from work, I'll take some pictures of what I'm talking about and post them to give you an idea.

 

[Bradley Keck]

I had a similar issue with high TDS out of the RO, the higher the pressure in the system the higher the tds out. This could be what you are seeing by adding back pressure of the DI. My RO housing had a crack that allowed the waste water to leak into the RO output. I replaced the housing and worked as usual. It sounds like you have a leak either it's the housing or membrane.

I replaced the housing, but I am starting to wonder if this new membrane is shot from being in the old housing and with the old regulator for about 20-30g worth of production. thank you for your help!

 

[Bradley Keck]

When you say line one, do you mean out of the membrane and into the DI stage?

Here is what I would do next, I would use what ever I had laying around to restrict the waste water line more.
Set it up again to run through the membrane only and put that shut off valve on the waste water line and partially close it until you get a 1:3 ratio. I know this is not the right way to do it, and not meant to be a long term solution, I just want to see if you start getting better rejection numbers with the proper ratio.

Can you take some more pics of your system and post them here? It would be helpful to see more of it from other angles and a shot showing the whole RODI system.

Yes. You are exactly right. Line 1/probe 1 is after the membrane and before the first DI canister. Does it make sense at all that my ratio can be 7/1 and 11/1 within a two day period and then at the same time have a bad rejection rate? If that is possible, can a high ratio and high TDS post-membrane be caused by a partiallt clogged membrane? Again, I cannot thank you enough for all your help. I will try restricting the waste line and post pics of the RODI system.

 

[Bradley Keck]

Hmmm, interesting stuff here. From experience and understanding how RO membranes work, when you add your resin canisters to the outlet of the RO unit, you create some backpressure that will reduce the efficiency of a membrane and increase your waste water to product water ratio (more waste water), but yours is quite excessive. It's starting to sound like you have a clog in your product lines as well or quite possibly in your auto shut off valve too. It may be worth taking all the lines off of your RO unit and inspecting them for clogs, and possibly replacing them as RO lines are cheap. Quick test would be to blow air through them with your mouth. It should be super easy. As for the auto shut off valve, some of them can be dismantled and inspected. I haven't used one for a long time as I've made mine all electronic. TMB is right about keeping your unit pressurized. I do the same to mine. So in summary, you have a new housing, new flush valve / restrictor, kind of new RO membrane, and the only other parts left to replace are the lines and the auto shutoff valve. I would strongly consider inspecting / replacing those and then run the unit with no resin canisters and see if your waste / product water ratio comes closer to 3:1. You can also temporarily remove the auto shut off valve and just connect the product line to product outlet of the membrane, and the restrictor / flushing valve to the waste outlet of the membrane (preferably with new tubing). That will take everything out of the picture and test just your membrane and membrane housing and let you know if it is the problem, or if it's your lines / auto shut off that is the issue. I hope that helps. Hope you have time to play mad scientist for a little while as this will get you to the problem. When I get home from work, I'll take some pictures of what I'm talking about and post them to give you an idea.

This is what I have been thinking too. I have pretty much changed everything but the lines (except waste line and product line I know are not clogged) and the auto-shut off. The kit came with another auto-shut off valve. I cannot tell a difference in size or anything. It has the same in and out marked on it. I'm just not sure why they included an extra? I could go ahead and hook up this other one. Are there different auto shut offs?