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

[Bradley Keck]

Bradley, when you changed out your housing and flow restrictor did you change your membrane too? If you made a fair amount of water with bad product to waste water ratio you may have mucked up your membrane to the point where you won't get great product TDS. I hate to say it, but it might be worth replacing it as well. The 75 GPD ones from BRS are awesome. I have 600 TDS and before replacing my membrane I was getting 18 on the outlet, now I get 4 on a brand new membrane. Either way, I would continue to monitor your waste water line when your flushing valve isn't open to make sure you don't get another clog somewhere or fouled restrictor.

The original membrane was replaced after < 200g of RODI made thinking that was the problem. The new one had only 30g of RODI made through it before the housing and flush valve were replaced. I cannot imagine it is already fouled up. I stopped making water for the most part except what I needed to fill of top off reservoir. I will keep monitoring my waste water line, but it is definitely better. I just hate to buy yet another membrane, but if I knew that would take care of it I would do it in heart beat. I'm just cannot imagine the newer membrane is already shot. Thank you for your help. I really need to get this figured out so I'm not wasting through so much di resin and can do a 30g water change in a week.

 

[Bradley Keck]

So, I can hear this slight "hiss" coming from the new flow regulator and noticed my pressure dropped from 52 to 47. My TDS are at 122 at line 1. I hooked up the old flow regulator and noticed no hiss, pressure at 52, and TDS at 194. Hooked the new one up again and the hiss could be heard again, the pressure dropped to 47, and the TDS dropped to 121. What to make of this?

 

[TMB]

Wow, this has been quite the ordeal for you on something that is normally pretty simple.

Now that you have all the new parts in place I would confirm these few things as a "new starting point".
RO waste/product ratio
Incoming TDS
Product TDS (before DI, just unhook that for now. no reason to burn it up testing your RO system)
System pressure while running.

There must be something wrong with this system somewhere. The data from above questions will help everyone find the issue.
I would take the time to accurately measure the ratio into measuring containers so you know for sure. You can basically just unplug everything and insert temporary lines into the 2 ports to do this measurement (product water out and waste water with flow restrictor in place). When I do this I pay attention to the product water and let it run to a measurable point in the container, then take a reading from the waste line. Rough estimates are fine for a system that is functioning properly, but this system has a problem and good data will help uncover the problem.

I know you've been through most of this before, but anytime I make changes to my RODI system I check these specs.

HTH

 

[Bradley Keck]

Wow, this has been quite the ordeal for you on something that is normally pretty simple.

Now that you have all the new parts in place I would confirm these few things as a "new starting point".
RO waste/product ratio
Incoming TDS
Product TDS (before DI, just unhook that for now. no reason to burn it up testing your RO system)
System pressure while running.

There must be something wrong with this system somewhere. The data from above questions will help everyone find the issue.
I would take the time to accurately measure the ratio into measuring containers so you know for sure. You can basically just unplug everything and insert temporary lines into the 2 ports to do this measurement (product water out and waste water with flow restrictor in place). When I do this I pay attention to the product water and let it run to a measurable point in the container, then take a reading from the waste line. Rough estimates are fine for a system that is functioning properly, but this system has a problem and good data will help uncover the problem.

I know you've been through most of this before, but anytime I make changes to my RODI system I check these specs.

HTH

Thank You! You know exactly what I have been thinking! I just want it to work like it use to so I can get on with starting my stocking process/schedule. I'm not in a big hurry, but I could get my first fish in a week if Ican get this working and do a 20% water change. I will remeasure all the above. I agree that would be a good place to start. I did the "cup method" before, so I will be sure to be exact as possible. Thanks again.

 

[TMB]

Post your results and then we can go from there.

 

[3mm3]

Hello everyone!

I'm in the process of setting up my first saltwater aquarium, a 150g 60x24x24. I have a BRS 6 stage RODI 75gpd unit. I finished my salt mixing station back in June and decided to go ahead and try it out although I was not ready to fill the tank. I made 100g of RODI and my TDS after the membrane read about 20-40 typically. After a total of about 150g of RODI, I had depleted almost one cartridge of DI resin. I stored the RODI until the beginning of August when the tank was ready to be leak tested and filled. Once I got the tank filled, I started to make more RODI. The TDS after the membrane all of sudden started reading as high as the 180's! I went through a whole cartridge of DI resin after only 20-30g, and it seemed to take much longer to make RODI water. I live in Indianapolis. The average TDS straight from the tap is around 400TDS with some areas a slow as 200 and some as high as 600. My pressure has consistently been at 50PSI both when it was working right and now. I contacted BRS and they suggested maybe a faulty membrane, so I bought another. Made no difference. I have run another 40g through the new membrane and am still getting readings in the 160-190 range after the membrane. The TDS after the first and 2nd di cartridge does read 0, but like I said, I am going through DI resin like crazy.. I contacted a LFS that uses city water, and they have not experienced any problems that they are aware of. Any ideas what the heck is going on? For good measure, even though I detect no ammonia in the RODI water and my pressure has not dropped, I replaced both carbon blocks and sediment filter. It made no difference.

I'm having the exact problem with my new membrane.. Purchasing a booster pump to see how it helps. My numbers. TDS into system 73 after new filters and membrane 17.....

 

[TMB]

I'm having the exact problem with my new membrane.. Purchasing a booster pump to see how it helps. My numbers. TDS into system 73 after new filters and membrane 17.....

I'm no expert on RODI systems, but those numbers are way off too. As an example my incoming TDS is ~900, and the permeate (product) is 17 before the DI stages. The extremely high TDS at my house is what caused me to learn as much as possible about RODI systems.

I think you should do the same tests:
TDS in
TDS out
Working pressure
Permeate/Waste ratio
and possibly a picture of your system.

Post back what you find.

 

[3mm3]

I'm no expert on RODI systems, but those numbers are way off too. As an example my incoming TDS is ~900, and the permeate (product) is 17 before the DI stages. The extremely high TDS at my house is what caused me to learn as much as possible about RODI systems.

I think you should do the same tests:
TDS in
TDS out
Working pressure
Permeate/Waste ratio
and possibly a picture of your system.

Post back what you find.

TDS in: 73
TDS out: 17 before di resin 0 after resin
Working pressure: 51 psi between membrane and pre-filters
Permeate/Waste ratio: 167 grams waste to 146 grams product. To get this measurement I ran the ro system for a few minutes then measured.

Later this weekend I'm going to do a full tear down and look everything over. Never had an issue like this before..

 

[TMB]

@3mm3 it seems to me that you might try reseating the membrane. Unless you’re running a 1:1 system it looks like the membrane is leaking from one side to the other. Meaning that the waste water side is leaking into the product side. Or I guess it could be that your flow restrictor is partially plugged, but I think it would work that way for a while until it clogged up the membrane. I could be wrong there, but I would still start with reseating the membrane.

 

[Bradley Keck]

I'm having the exact problem with my new membrane.. Purchasing a booster pump to see how it helps. My numbers. TDS into system 73 after new filters and membrane 17.....

Wow, 73 is actually pretty good for source water. Sorry to hear you are having a similar problem. I had to paint our kitchen and put up new window treatments yesterday. Work today and then a dinner outing this evening. I plan on getting updated measures tomorrow. Hopefully yours will be easier to solve!

 

[Bradley Keck]

Here are my latest measurements after replacing the membrane housing and flow regulator/flush valve. My source water TDS = 329, initial TDS at line 1 = 122, after 5 minutes = 112, and after 20min = 128. That is better. It was reading anywhere from 180-190's before, but still no where close. My pressure has dropped a little since adding this new regulator and I can hear a slight "hiss" coming from it. Installed the old one and no hiss. My pressure is 48 instead of 52. My waste to RODI ratio is more like what I would expect and instead of being reversed it is 7.5/1. I have a constant flow coming from the waste water line now instead of slight drip. Still not fixed, but different and overall better. I'm still going through DI resin like crazy. I went through a half a canister just to make about 15g of RODI.

 

[TMB]

Here are my latest measurements after replacing the membrane housing and flow regulator/flush valve. My source water TDS = 329, initial TDS at line 1 = 122, after 5 minutes = 112, and after 20min = 128. That is better. It was reading anywhere from 180-190's before, but still no where close. My pressure has dropped a little since adding this new regulator and I can hear a slight "hiss" coming from it. Installed the old one and no hiss. My pressure is 48 instead of 52. My waste to RODI ratio is more like what I would expect and instead of being reversed it is 7.5/1. I have a constant flow coming from the waste water line now instead of slight drip. Still not fixed, but different and overall better. I'm still going through DI resin like crazy. I went through a half a canister just to make about 15g of RODI.

Wait a minute... are you saying that you have 7.5 parts product/ 1 part waste? Or the reverse”
You should have 1 part product/ 4 parts waste. If the Product/ waste ratio is actually 1:7 meaning 1 part product to 7 parts waste. This is likely a problem. We need to get it down to 1:4 and then go from there.

I would not worry about a hiss from the restrictor, instead be trying to get enough restriction to make the membrane work.

 

[pwilliaml]

OK, a couple things here. Your waste water to product water ratio varies depending on the setup you have. The ratio is determined by the size of the flow restrictor you have. Below is the chart directly from BRS:
Restrictor / Suggested RO Membrane
200 mL / 20-30 GPD
300 mL / 30-40 GPD
350 mL / 40-55 GPD
550 mL / 55-75 GPD
800 mL / 75-100 GPD
800 mL / 100-150 GPD
Those are based on the straight restrictor. They have a membrane flush valve as well which is just a bypass valve and a restrictor built into one device.

Now if you have a stock BRS 75 GPD RO unit with the stock 550 mL/min flow restrictor, you should have a waste water to product water ratio of 3 to 1, or 3 gallons of waste for every 1 gallon of product water. You should be pretty close to this with 50 psi of input pressure. Also, you will see a slight drop in pressure with a properly sized restrictor. Normally, when you open up the flushing valve, your inlet pressure will drop, and then when you close the flushing valve, it will come back up to just under your normal water supply pressure depending on how clogged your filters are. I'm assuming your pressure gage is right before the membrane. Correct me if I'm wrong.

As for the hissing sound, when your restrictor is on service and not being bypassed you should here a hissing sound as it is forcing 50 psi water through a very small hole. That's how they work. If you are getting 7.5 gallons of waste water for every 1 gallon of product water, then your bypass / flushing valve may be open, your restrictor valve or combination restrictor / flushing valve is larger than the standard 550 mL, or you have another problem.

So please update us on your RO membrane size (guessing 75 gpd), your restrictor size (should be 550 mL), and your waste water to product water ratio. Thanks, and let's get this fixed and working for you. Please correct any of the guesses I made here on your system.

 

[pwilliaml]

Also, it doesn't take long for a membrane to get all fouled up if your system isn't operating properly. If you're worried about spending too much money on this, a new membrane is only $23.68 on Amazon with free shipping if you search for Filmtec BW60-1812-75 75 GPD Filmtec Residential RO Membrane. You can have it in 2 days too if you have Prime. Once we get your ratios and everything right, I'd invest in a new membrane. You should have 98 to 99% rejection rate on a new membrane calculated by (TDS in - TDS out) / (TDS in).

 

[KStatefan]

Here are my latest measurements after replacing the membrane housing and flow regulator/flush valve. My source water TDS = 329, initial TDS at line 1 = 122, after 5 minutes = 112, and after 20min = 128. That is better. It was reading anywhere from 180-190's before, but still no where close. My pressure has dropped a little since adding this new regulator and I can hear a slight "hiss" coming from it. Installed the old one and no hiss. My pressure is 48 instead of 52. My waste to RODI ratio is more like what I would expect and instead of being reversed it is 7.5/1. I have a constant flow coming from the waste water line now instead of slight drip. Still not fixed, but different and overall better. I'm still going through DI resin like crazy. I went through a half a canister just to make about 15g of RODI.

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"?

 

[pwilliaml]

TDS in: 73
TDS out: 17 before di resin 0 after resin
Working pressure: 51 psi between membrane and pre-filters
Permeate/Waste ratio: 167 grams waste to 146 grams product. To get this measurement I ran the ro system for a few minutes then measured.

Later this weekend I'm going to do a full tear down and look everything over. Never had an issue like this before..

3mm3, your waste water to product ratio is too low. You should virtually always have more waste water than product water, even if you have the 150 gpd water saver add on from BRS which I hope you don't if you only have 51 psi of input pressure. Hopefully you have the 75 gpd membrane and a 550 mL restrictor. It sounds like you might have a clogged restrictor too. People don't realize it, but these restrictors need to be replaced every year or 2 at most especially if you have hard water. When you shut off your system and the water in the waste water line dries, it deposits whatever minerals were in the water onto the lines and your restrictor which is a very small hole and can foul it up quickly.

 

[Bradley Keck]

Wait a minute... are you saying that you have 7.5 parts product/ 1 part waste? Or the reverse”
You should have 1 part product/ 4 parts waste. If the Product/ waste ratio is actually 1:7 meaning 1 part product to 7 parts waste. This is likely a problem. We need to get it down to 1:4 and then go from there.

I would not worry about a hiss from the restrictor, instead be trying to get enough restriction to make the membrane work.

It's 1part product to 7.5 parts waste.

 

[Bradley Keck]

OK, a couple things here. Your waste water to product water ratio varies depending on the setup you have. The ratio is determined by the size of the flow restrictor you have. Below is the chart directly from BRS:
Restrictor / Suggested RO Membrane
200 mL / 20-30 GPD
300 mL / 30-40 GPD
350 mL / 40-55 GPD
550 mL / 55-75 GPD
800 mL / 75-100 GPD
800 mL / 100-150 GPD
Those are based on the straight restrictor. They have a membrane flush valve as well which is just a bypass valve and a restrictor built into one device.

Now if you have a stock BRS 75 GPD RO unit with the stock 550 mL/min flow restrictor, you should have a waste water to product water ratio of 3 to 1, or 3 gallons of waste for every 1 gallon of product water. You should be pretty close to this with 50 psi of input pressure. Also, you will see a slight drop in pressure with a properly sized restrictor. Normally, when you open up the flushing valve, your inlet pressure will drop, and then when you close the flushing valve, it will come back up to just under your normal water supply pressure depending on how clogged your filters are. I'm assuming your pressure gage is right before the membrane. Correct me if I'm wrong.

As for the hissing sound, when your restrictor is on service and not being bypassed you should here a hissing sound as it is forcing 50 psi water through a very small hole. That's how they work. If you are getting 7.5 gallons of waste water for every 1 gallon of product water, then your bypass / flushing valve may be open, your restrictor valve or combination restrictor / flushing valve is larger than the standard 550 mL, or you have another problem.

So please update us on your RO membrane size (guessing 75 gpd), your restrictor size (should be 550 mL), and your waste water to product water ratio. Thanks, and let's get this fixed and working for you. Please correct any of the guesses I made here on your system.

Thank You for your help here. You are correct that I have stock 75gpd BRS RODI unit with the 550 on it. Glad to know there should be a hiss. That would explain why the old one was not working and I heard no hiss from it. The pressure does drop when I open the flush valve to about 33 PSI and then goes back up to 48 when I close it. I am indeed getting 7.5/1 I measured by filling one typical plastic up with RODI and 7.5 cups of waste water to get the one cup of RODI. This was a brand new restrictor/flush valve and membrane housing sent by BRS that are getting me these measurements.

 

[Bradley Keck]

3mm3, your waste water to product ratio is too low. You should virtually always have more waste water than product water, even if you have the 150 gpd water saver add on from BRS which I hope you don't if you only have 51 psi of input pressure. Hopefully you have the 75 gpd membrane and a 550 mL restrictor. It sounds like you might have a clogged restrictor too. People don't realize it, but these restrictors need to be replaced every year or 2 at most especially if you have hard water. When you shut off your system and the water in the waste water line dries, it deposits whatever minerals were in the water onto the lines and your restrictor which is a very small hole and can foul it up quickly.

So its 7.5 waste/1 part RODI. It was the totally flipped before replacing the membrane housing and restrictor/flush valve. Now its the other way around and I have too much waste to product

 

[TMB]

It's 1part product to 7.5 parts waste.

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.