Ro/di tds help

Titobattilocchi · 09/08/2013, 05:27 PM

So I'm getting 002 to 004 TDS after my RO membraine it is also reading that after my max cap DI. I think it is my RO membraine that is bad but not for sure? The DI is new just replaced two weeks ago or so. The reading before the RO membraine is reading at 104 TDS can some one give me some help or other things I need to check. I just ordered a new RO membraine today. How do I know when to change the DI unites I have two running piggy back.

on the spot · 09/08/2013, 05:35 PM

You didn't need a new RO membrane. 2ppm after the RO for you is 98% rejection. Pretty darn good. I'd look at your TDS meter first. If you don't see a change from 2 to zero with new resin something is wrong.

Titobattilocchi · 09/08/2013, 05:42 PM

It's just been at that reading for some time now and it seems to go up then down I will watch it as its running and it will change from 002 and go up to 005 then back down.

on the spot · 09/08/2013, 06:45 PM

Quote:

Originally Posted by Titobattilocchi

It's just been at that reading for some time now and it seems to go up then down I will watch it as its running and it will change from 002 and go up to 005 then back down.

Even if that fluctuation is post RO I wouldn't worry about that - it's moving between 95 and 98%...but the DI should be zero, especially when new.

Where did you get the meter, and how long ago? I'd email or call them Monday to see about a replacement if it's fairly new.

thegrun · 09/08/2013, 06:46 PM

002-004 after the Ro is great! What is your tap water tds? If you entering your DI at .004 then the problem is with the DI, not your RO filter. When did you last change your resin?

Titobattilocchi · 09/08/2013, 06:57 PM

Tap water is 104 ppm before RO membrane. Just replaced Max cap DI about 2 weeks ago

dkeller_nc · 09/08/2013, 08:14 PM

Something is indeed wrong - either your TDS meter is a bit "off", or your resin may have developed a channel. Ideally, you want to run a DI resin that has a color indicator in it. Color indication isn't completely bomb-proof, but it does give you an idea of close to exhaustion your resin is.

What I mean by a "channel" is that any particulate media can develop a "short cut" through the media that allows some amount of water to leave the cartridge largely untreated.

If what you have is the typical set-up for a DI cartridge (a clear plastic refillable cartridge), then you can remove it from the unit, turn it upside down and give it a few gentle whacks on the counter. That is usually enough to close a channel if one exists.

One check you might consider is buying a jug of distilled water from the grocery store and checking it with your TDS meter. It should read zero (be sure that you get distilled water and not "purified" water).

If your meter checks out OK, and your resin is truly exhausted, then it's possible that your RO membrane may have developed a by-pass leak in the housing. That allows a little untreated water to get by your RO membrane and will rapidly exhaust your resin.

All this said, so long as your carbon filter is good (i.e., replaced within the last couple of months), your water should more than likely be perfectly fine for your tank's use at 1 or 2 ppm TDS.

09/08/2013, 05:27 PM	#1
Titobattilocchi Registered Member Join Date: Apr 2013 Location: Eureka, CA Posts: 131	Ro/di tds help So I'm getting 002 to 004 TDS after my RO membraine it is also reading that after my max cap DI. I think it is my RO membraine that is bad but not for sure? The DI is new just replaced two weeks ago or so. The reading before the RO membraine is reading at 104 TDS can some one give me some help or other things I need to check. I just ordered a new RO membraine today. How do I know when to change the DI unites I have two running piggy back.

09/08/2013, 05:35 PM	#2
on the spot Registered Member Join Date: Oct 2007 Location: West Michigan Posts: 1,010	You didn't need a new RO membrane. 2ppm after the RO for you is 98% rejection. Pretty darn good. I'd look at your TDS meter first. If you don't see a change from 2 to zero with new resin something is wrong.

09/08/2013, 05:42 PM	#3
Titobattilocchi Registered Member Join Date: Apr 2013 Location: Eureka, CA Posts: 131	It's just been at that reading for some time now and it seems to go up then down I will watch it as its running and it will change from 002 and go up to 005 then back down.

09/08/2013, 06:46 PM	#5
thegrun Registered Member Join Date: Dec 2008 Location: Garden Grove, Ca Posts: 17,023	002-004 after the Ro is great! What is your tap water tds? If you entering your DI at .004 then the problem is with the DI, not your RO filter. When did you last change your resin?

09/08/2013, 06:57 PM	#6
Titobattilocchi Registered Member Join Date: Apr 2013 Location: Eureka, CA Posts: 131	Tap water is 104 ppm before RO membrane. Just replaced Max cap DI about 2 weeks ago

09/08/2013, 08:14 PM	#7
dkeller_nc Registered Member Join Date: Mar 2013 Location: Central NC Posts: 5,062	Something is indeed wrong - either your TDS meter is a bit "off", or your resin may have developed a channel. Ideally, you want to run a DI resin that has a color indicator in it. Color indication isn't completely bomb-proof, but it does give you an idea of close to exhaustion your resin is. What I mean by a "channel" is that any particulate media can develop a "short cut" through the media that allows some amount of water to leave the cartridge largely untreated. If what you have is the typical set-up for a DI cartridge (a clear plastic refillable cartridge), then you can remove it from the unit, turn it upside down and give it a few gentle whacks on the counter. That is usually enough to close a channel if one exists. One check you might consider is buying a jug of distilled water from the grocery store and checking it with your TDS meter. It should read zero (be sure that you get distilled water and not "purified" water). If your meter checks out OK, and your resin is truly exhausted, then it's possible that your RO membrane may have developed a by-pass leak in the housing. That allows a little untreated water to get by your RO membrane and will rapidly exhaust your resin. All this said, so long as your carbon filter is good (i.e., replaced within the last couple of months), your water should more than likely be perfectly fine for your tank's use at 1 or 2 ppm TDS.