Higher TDS after replacing filters and resin?

[azreefkeeper]

Hi All,

What I thought to be a simple maintenance seems to have become more complicated. I have a 4-stage BRS RODI filter system that has been running well for about a year. In the last few weeks its been producing 2 TDS water and I could tell the resin was on the way out.

I ordered a filter replacement pack from BRS last week and replaced it this afternoon. After running about 50 gal of water I'm still measuring 3 TDS on the "In" and 4 TDS on the "Out". Higher output was something I've never seen before. What should I consider next? Run more water through and cross my fingers? Readjust the filters where they screw in? I can't see anything wrong with how they are screwed in now. Also, I made sure to pack the resin tight and flushed the membrane for a good 5 - 10 min.

Input pressure to the unit is 66psi.

 

[fuelman]

You didn't accidentally put the di cartridge back in upside down did you? I did that once lol. check to make sure the rubber seal on the cartridge is facing up to the top of the unit

 

[azreefkeeper]

You didn't accidentally put the di cartridge back in upside down did you? I did that once lol. check to make sure the rubber seal on the cartridge is facing up to the top of the unit

Hi fuelman,

No, the DI container (within the canister) only has one end with a rubber ring. The other end (bottom) has a screw cap that rests on the bottom of the canister. I can pull it off and examine it just be sure though. Thanks for the reply!

 

[fuelman]

Hi fuelman,

No, the DI container (within the canister) only has one end with a rubber ring. The other end (bottom) has a screw cap that rests on the bottom of the canister. I can pull it off and examine it just be sure though. Thanks for the reply!

You're welcome. It's the only thing I can think of I did it once didn't realize it & started getting higher readings coming out than going in.

 

[BT_NEM]

It could be the ro membrane, has it ever been replaced?

 

[azreefkeeper]

Just for kicks I pulled of the DI canister and took another look at the resin container inside. It was right-side up and I see there is an embossed indicator that says "this end up" so it's correct. DI resin looks nice and tightly packed still. When I turned it upside down for about 30 seconds some water started to come out of the top so I know water is getting in. It's just odd...I'll run some more water through the system to see if I can get the TDS to read clean again.

After another 25 gallons or so I will check the seating on the sediment filter and the carbon block. I will run outta options after that I think. That sucking sound I just heard was my ATO complaining that it needs water now so I may just bite the bullet and use what's coming out for the next day or so.

 

[azreefkeeper]

Hi BT_NEM,

I have not, but a few things make me not suspect the RO membrane. First, the unit was producing 2 TDS water just earlier this morning and second, the TDS after the membrane (before the DI unit) is measuring 3 TDS.

That seems pretty low. I haven't tested the tap water going in, but I suspect it's much higher than that and my rejection rate is probably reasonable if I'm getting 3 TDS on the input side to the DI chamber. That said, I may be mixing up how these are sampling the water. I've pretty much just mounted this thing on the wall and run "as is" since day one.

 

[Spieg]

Just throwing out some ideas - If the system has a back-flush valve for the RO membrane, be sure it is in proper position. Did you by any chance fiddle around with the TDS probes when you replaced the filter media? The metal probes need to be oriented correctly in the probe housing or they won't read accurately.

 

[9975]

Any updates to this? I'm curious as to a hopefully good outcome for you

 

[jjencek]

I had the same problem. The issue was improperly packed resin. I repacked the resin and it was solved. I later read something about water channels through an improperly packed resin.

 

[dadnjesse]

This is a Membrane TDS rejection rate calculator. I know you didn't replace the membrane but may find it useful. The same thing happens to me when I change mine.

RO Rejection Rate Calculator

Aquarium calculator; Estimate the rejection rate of a reverse-osmosis (RO) filter.

www.hamzasreef.com

 

[azreefkeeper]

Any updates to this? I'm curious as to a hopefully good outcome for you

Hi All,

So I didn't have a chance to look at it again until tonight, which was fine since I had enough RO water set aside to keep my ATO full. I watched a few BRS videos on the system to see if I managed to do something wrong then I went through all 3 canisters step-by-step. The sediment filter and carbon block both look to be oriented just right and I didn't change anything to any of the connections.

Spieg, I did validate the RO membrane flush valve was correct. You can pretty much tell when it is flushing because water jets out of the waste-water tube pretty loudly when it is. I also double-checked the TDS probes to make sure they were oriented so water would flow through the tines. Both looked correct, although rotating them didn't seem to change the TDS reading noticeably.

I removed, inspected, and repacked the DI resin chamber but honestly, it looked to be packed pretty tightly already and I don't see any evidence of channeling. Right now the #1 TDS meter (after the first two chambers and the RO membranes) is reading at 3 TDS. The output of the DI resin chamber (meter #2) is still reading at 5 TDS. It's as if the resin itself is adding instead of pulling out dissolved solids.

At this point I'm at a loss. The resin is brand new BRS color-changing nuclear resin. It should be stripping that down to 0 TDS no problem. I'll keep running water through the system for a good while. Water is the ultimate solvent...hopefully enough of it will get this to run clean soon.

 

[X-37B]

First thing I would do is get more di resin and change it.
You may have got a bad batch. It can happen.
If you were getting 1 out of your membrane before the change then I would get new carbon also.
I would get a hand held tds meter to test the effluent to verify the reading.
I have one and always like to check my city water to know the level.
Plus you can calibrate them with a standard.
In some areas city waters tds can vary quite a bit throughout the year.
I also have the 4 stage and my city water is 40 ish so pretty low.
I get 1 comming out of the ro and 0 out of the di.
I also bought mine used and have no idea how much water has been run through the membrane.
I also flush the membrane for 15 minutes before and after each use.
I make 275 gallons at a time now and replace with the brs 3 pack when di reads 1.

 

[azreefkeeper]

All,

Thanks for all the great feedback! So after running about 250-300 gallons through the system I'm still at an impasse. The output from the RO membranes (2) is still reading 2 TDS which is pretty close to what it's always been. The output from the DI Resin chamber is reading 4 TDS.

This has got my wheels turning...I changed all of my filtering (Sediment, Carbon block, Resin) because my TDS had risen to 3-4 consistently. After changing all filters and THEN watching about 5-6 videos, including the BRS "Beware these RO/DI mistakes" it started to dawn on me that my filter media and DI resin looked much less "filthy" than anything I saw on those videos. Although my resin was about 3/4 brown/yellow, it was not THAT bad. My other filters looked clean and white. The system had been running for about 12 months.

Perhaps the issue is the TDS probe on the output of the DI resin canister? Thing is, you can't replace these individually. I would have to replace the entire dual inline TDS is meter and probes which costs about $30. Still not much more than buying a hand-held TDS which may or may not be as accurate as the inline probe.

All this said I'm not sure how to pull these MUR-loc fittings out to replace them. Does anyone know what the trick is without damaging the tubing?

 

[dadnjesse]

Push the white circle part on the T that the probe pushes into then carefully pull it out.

 

[Garf]

Are you gonna try putting the IN on the OUT, to see if it is actually defective?

If you turn on the meter when the probe is dry and in air, it should read zero, if it’s working ok.

 

[azreefkeeper]

Are you gonna try putting the IN on the OUT, to see if it is actually defective?

I could certainly try that to be sure. I just didn't want to mess with it at first. Seeing how easy it should be to get these apart I will definitely take that step to isolate if there is a bad probe here.

Thanks for the suggestions all!

 

[Garf]

I could certainly try that to be sure. I just didn't want to mess with it at first. Seeing how easy it should be to get these apart I will definitely take that step to isolate if there is a bad probe here.

Thanks for the suggestions all!

Re read my post, I may have edited it since you looked.

 

[nukemdanno]

Did you change these out?

And is this what you bought?

 

[azreefkeeper]

Are you gonna try putting the IN on the OUT, to see if it is actually defective?

If you turn on the meter when the probe is dry and in air, it should read zero, if it’s working ok.

That does sound like an easier approach. I will give that a try first since the #2 probe is so easily accessible...



Thanks!