80+ TDS after membrane. Could use some help.

[Shane B.]

New to the hobby. Located in central OH, very hard city water coming into the home, with chlorine added for good measure.

Water comes into RO from the softener, through 1 sediment filter, 2 standard carbon filters, my RO membrane, and then 2 DI canisters. From here the water splits to a storage bucket for water changes and a pressurized tank for drinking water. TDS readings post RO membrane are all over the place the last few days after being stable for 2+ months.

TDS after softener and before RO: ~420. Hasn't changed much since I set up the system.
PSI prior to membrane: 42 PSI. Again, not much change here since I set up the system.
TDS after RO membrane: 70-80, as high as 250(!!!!) Was around 4-6.
TDS after DI: 0

I feel like I can watch my DI resin change color in real time, which hurts my wallet. Our water tastes fine, and I'm not hurting right now as I don't have any livestock and my tank cycle isn't even complete. However, I am worried that this high TDS could cause problems in the future with water changes. I had no issues until I changed my first DI canister, then things went sideways. However my last maintenance wasn't even on the RO parts of my system. All I did was change out the used DI. I've flushed the membrane a few times over the last few days to no avail.

Coming to the community for guidance.

 

[COreef8]

New to the hobby. Located in central OH, very hard city water coming into the home, with chlorine added for good measure.

Water comes into RO from the softener, through 1 sediment filter, 2 standard carbon filters, my RO membrane, and then 2 DI canisters. From here the water splits to a storage bucket for water changes and a pressurized tank for drinking water. TDS readings post RO membrane are all over the place the last few days after being stable for 2+ months.

TDS after softener and before RO: ~420. Hasn't changed much since I set up the system.
PSI prior to membrane: 42 PSI. Again, not much change here since I set up the system.
TDS after RO membrane: 70-80, as high as 250(!!!!) Was around 4-6.
TDS after DI: 0

I feel like I can watch my DI resin change color in real time, which hurts my wallet. Our water tastes fine, and I'm not hurting right now as I don't have any livestock and my tank cycle isn't even complete. However, I am worried that this high TDS could cause problems in the future with water changes. I had no issues until I changed my first DI canister, then things went sideways. However my last maintenance wasn't even on the RO parts of my system. All I did was change out the used DI. I've flushed the membrane a few times over the last few days to no avail.

Coming to the community for guidance.

There could be a few issues causing this but the red flag I see is your water pressure, 42 PSI is pretty low. The RO membrane requires a decent amount of pressure to produce low TDS water but for most single membranes I think about 50 PSI is the minimum. You can try adding a booster pump to increase your pressure. That should help.

Also, you may know this but every time the system is turned on (either manually or to automatically refill the pressure tank) the RO membrane will put out high TDS water for a minute or so. This is TDS creep and it can definite eat through your DI resin quickly if the system is constantly turning on and off.

 

[Shane B.]

Going to look at ordering a pump and replumbing the setup so only the RO feeds the pressure tank and not the DI. I don't mind drinking 20 ppm water, but do mind replacing DI twice a month.

 

[JoshH]

How long has the system been set up? And do you know if your city uses chloramines or chlorine? It sound like your membrane is shot and you will need a new one with 80 TDS getting through.

 

[Shane B.]

That is part of my problem. The DI part is only 2 months old, and the RO system is fairly old. I do not remember the last time I changed the RO membrane. So i think it may be that. I will order a new membrane and try that before I spend even more money on a pump.

As far as I know, yes my city does use chlorine in our water. So I should probably get my hands on a better carbon filter and change those out more regularly.

 

[JoshH]

When was the last time you changed the carbon blocks?

Also might still be a good idea to get the pump anyway, at 42 PSI your membrane is certainly not performing up to snuff and a replacement membrane still won't be performing as well as it should. Might I suggest looking into Spectrapure membranes for a replacement as they will handle the high TDS better than most others.

 

[PatW]

You might need a booster pump to increase the pressure. Replacing your RO membrane might be necessary. A 98% rejection rate would give you an 8 tds post RO membrane and most membranes should do that. Spectrapure sells membranes that have 99% rejection so one of those may be worth it.

Also water softeners replace ions with sodium so you might get away with just RO.

 

[Shane B.]

Thanks all. I'll look at a new membrane and pump and report back in a week or so.

 

[JoshH]

Thanks all. I'll look at a new membrane and pump and report back in a week or so.

I would also look to replacing your carbon blocks as well, be sure to flush them out before hooking them up to the membrane. As I mentioned earlier they are probably spent and that lead to the burned out membrane.

 

[Hitman]

I would also look to see if you can plumb it before the water softener. My carbon blocks and membrane last twice as long now that I ran a hose to the main line pre softener. The booster pump is a good idea as well. I have 90psi per my BRS gauge.

 

[Opus]

Check out Premium Aquatics. They are running a 15% off sale this weekend and have the 99% spectrapure membrane. I have that membrane and my 400+ tds tap water gets down to around 3 before the di. As others stated, you should also look into getting a pump for the system to run efficiently. Also get new prefilters, sediment and carbon. As a rule of thumb, they should be changed out every 6 months. If the carbon block is spent and chlorine gets past it, then the chlorine will eat holes in your RO membrane.

Lastly, you do need to tee off from the RO membrane for your drinking water. DI material is not food grade rated and is not recommended for drinking.

 

[Shane B.]

Check out Premium Aquatics. They are running a 15% off sale this weekend and have the 99% spectrapure membrane. I have that membrane and my 400+ tds tap water gets down to around 3 before the di. As others stated, you should also look into getting a pump for the system to run efficiently. Also get new prefilters, sediment and carbon. As a rule of thumb, they should be changed out every 6 months. If the carbon block is spent and chlorine gets past it, then the chlorine will eat holes in your RO membrane.

Lastly, you do need to tee off from the RO membrane for your drinking water. DI material is not food grade rated and is not recommended for drinking.

Did exactly this over the course of this morning during my normal chores. Fixed the plumbing so now RO goes to the tap instead of DI. Ordered an RO pump and new sediment and carbon filters along with a new membrane.

 

[Shane B.]

Update - I think I messed up

I bought the booster pump and it brought me up to 80 psi. Bought new DI resin (was out), sediment filter, chlorine blocking carbon filter, 1 micron carbon filter, and Spectrapure RO Membrane. I replaced EVERYTHING. Hooked it up, let it run for 20 minutes, tested, and got a reading of 140 TDS with 2 different meters.

I will admit, I forgot to flush the sediment and carbon blocks after changing them out. I just ran the whole system brand spanking new.

Did i kill my RO membrane by not flushing the carbon blocks? That is the only thing I can think of as to why I am seeing high TDS after replacing literally everything to do with my RO/DI system.

 

[COreef8]

Sediment filter doesn’t really matter but I believe the carbon blocks should be flushed for about 10-15 minutes. I still think TDS that high is odd unless you had 3,000+ TDS going into the membrane.

RODI systems are a mess of tubing and it might be possible that the tubing is not connected correctly. Can you post some pictures?

 

[rock_lobster]

aaaaaa

 

[Shane B.]

Here is my very poor attempt to show how i'm plumbed. If i had just set this up I would try to replumb it, but it ran just fine for around 4 months. When I changed up the filters then my TDS went sky high. Changed things again, still high TDS after the membrane. I suspect either bad RO membrane or bad auto shut off valve???

 

[COreef8]

Here is my very poor attempt to show how i'm plumbed. If i had just set this up I would try to replumb it, but it ran just fine for around 4 months. When I changed up the filters then my TDS went sky high. Changed things again, still high TDS after the membrane. I suspect either bad RO membrane or bad auto shut off valve???

Looks right to me. Looking at your first post, that's weird that is started suddenly when it was previously between 4 and 6 tds.

Where does the water go from that tee after the shut off valve? If it was a bad shutoff valve, you'd be able to hear it. I would just keep running water down the drain even when the system is not producing water.

Could be a bad restrictor valve too, what flow rate is the restrictor? If it is working correctly, there should be a steady flow of water, but it should not be shooting out of the drain line.

 

[Shane B.]

After the shut off valve, that first T goes to a pressure gauge. Then another T down that splits, one way to my DI system, another to my drinking water in the kitchen.

I did recently put on a new restrictor with the backwash thingy, but putting the old one back on did not help. Still at 145 TDS after letting the system run for 30 minutes or so.

I will check the valve and see what happens, but I am not hopeful.

I am beginning to suspect I may have fouled the new membrane by not flushing the carbon pre-filters like I should have.

 

[COreef8]

After the shut off valve, that first T goes to a pressure gauge. Then another T down that splits, one way to my DI system, another to my drinking water in the kitchen.

I did recently put on a new restrictor with the backwash thingy, but putting the old one back on did not help. Still at 145 TDS after letting the system run for 30 minutes or so.

I will check the valve and see what happens, but I am not hopeful.

I am beginning to suspect I may have fouled the new membrane by not flushing the carbon pre-filters like I should have.

Ok I doubt it has anything to do with the plumbing since it worked well before, but just to be sure, the tee on the far left goes only to a pressure gauge right? What about that gray tee? I can't see where that line is coming from.

Sorry for the RODI interrogation, lol. I'd just hate to see you buy a bunch more stuff to find out it was just a single wrong connection.

 

[Shane B.]

Correct - T on the left after the membrane that you can see only goes to a pressure gauge.
Gray T that you asked about = 1st inline TDS meter, coming right out of the supply from my water softener. Usually reads about 430 or so, hasn't changed a lot since i first installed it.
I checked the drain, steady drip. For giggles I checked the TDS and it was almost 500, so it makes sense to me that is the drain line.
I checked the TDS of the water coming right out of the membrane housing before the auto-shut off, any T's, etc. Still at 163.
Could my membrane housing be bad? Is that something that happens? Like drain water leaking into the output chamber?