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View Full Version : RODI looks dirty but TDS reads 0


RoTTen2TheCore
12/30/2008, 03:30 PM
So i've had my Ro/Di unit for about 2 years now and have never changed any of the filters or resin. I know you are supposed to change them every 6 months to a year or depending on the reading on a TDS. So i decided to take apart the unit and have a look and the inside of the casings and the filter were covered in a rust colored residue which doesn't smell like anything so i dont think its bacterial. So i manually rinsed out everything and before deciding to buy new filters i bought a TDS meter to see how bad it was and despite everything it is reading 0 and my tap water is at about 85.
Sooooooooooooo my question would be can nitrates and amonia not be detected by a TDS and despite the reading of 0, the water is stil impure? Also any clue what the rust colored stuff is?

grayson
12/30/2008, 03:50 PM
any desolved nitrates or amonia should be detected by TDS.

a2fire2i
12/30/2008, 04:34 PM
all of the filters were covered in it or just the first sediment filter? also, what type of TDS meter did you buy?

AZDesertRat
12/30/2008, 04:38 PM
ALWAYS change the prefilter and carbon every 6 months like clockwork!!! The prefilter and carbon have absolutely noting to do with TDS and a TDS meter will tell you nothing about their condition, they are there to protect the RO membrane which does take care of TDS.
You need to change filters immediately if not sooner and make darn sure you disinfect the system while you have it down, this is very important.
Use your TDS meter and test the tap water TDS, RO only TDS before DI and finally the RO/DI TDS to determine the condition of the membrane.

a2fire2i
12/30/2008, 04:44 PM
rat,
could you post a link on to how disinfect?

RoTTen2TheCore
12/30/2008, 04:47 PM
all the filters including the membrane a bit were covered in the stuff and i bought an HM digital handheld TDS. Ill test those seperate stages in my unit and let you know what the readings are

RoTTen2TheCore
12/30/2008, 05:08 PM
Ok so what i got is:
Tap water: 90
Through carbon and prefilters:88
After membrane:1
After Resin: 0

So what is it in the carbon and prefilters that wont show up on tds?
Like i said, the filters dont smell like anything at all so i dont think there is any bacteria in them hence why i didnt bother disinfecting them before.

aquaman67
12/30/2008, 05:44 PM
Turn off the water supply to the system.

Remove all housings and remove all pre-filters and post-filters from the system including sediment filters, carbon filters, in-line filters, and deionization cartridges. Remove the reverse osmosis membrane(s).

Wash housings with a soft brush or cloth in warm soapy water. Rinse thoroughly to remove all soap. Don’t forget to carefully remove and wash all o-rings. Lubricate the o-rings with a small amount of silicone grease and reinstall them.

Fill each vertical housing with one cup of potable water and three to four tablespoons of household bleach, and with this sanitizing liquid still in the housings, screw them back on to the system.

Turn on the water supply a bit, allow water to fill the entire system, and assure water is flowing out of the waste line and the purified water line. Place the outlet of the drain tube and purified water tube slightly higher than the system to assure these tubes are full of the sanitizing solution. When the sanitizing solution has reached the outlet of each tube, and with the outlet of each tube placed above the rest of the system, shut off the water supply for 30 minutes.

After 30 minutes, turn the water supply on and assure that water exits the system from both the drain tube and the purified water port. Flush the sanitizing solution from the system for 5 to 10 minutes.

Turn off the water supply and install new filters, taking care to flush the filters as appropriate.

mmedeiros2
12/30/2008, 08:26 PM
The rust color is probibly iron.

AZDesertRat
12/30/2008, 11:52 PM
Way too much bleach aquaman. Bleach is approx 50,000 parts per million so a little bit goes a long way.

Remove the prefilter and carbon block(s). Add 2 or 3 spoonfulls of bleach to the prefilter housing and reinstal the empty housings. If not replacing the RO membrane at this time then disconnect the 1/4" line leading from the carbon block up to the membrane housing at the membrane side. Stick this line in a bucket or the sink. Turn the water supply on and allow the housings to fill completely. Shut the water off and let things sit for a couple minutes. A note here, the Centers for Disease Control in Atlanta GA has found that 0.5 parts per milion chlorine will kill just about anything known to man in about 5 minutes so more bleach is not better!
Now turn the water back on and flush the system until all chlorine odor has passed. Shut it off, install the new prefilter and carbon block(s), leave the line disconnected and turn the water back on once more to flush the new filters to waste and to purge any trapped air. After a minute of so turn it off, reconnect the line and turn it back on and you are up and running.
If you are replacing the membrane at this time forget disconnecting the line and remove the membrane from its housing and include it in the flush process before installing the new membrane. For the final flush make sure you always flush 3 to 5 gallons through a new membrane before connecting it to the DI cartridges or you will shorten DI life.
Its important to not let chlorine get to a membrane or it will do permanent damage.

WaterKeeper
12/31/2008, 12:20 AM
<a href=showthread.php?s=&postid=14047508#post14047508 target=_blank>Originally posted</a> by AZDesertRat
A note here, the Centers for Disease Control in Atlanta GA has found that 0.5 parts per milion chlorine will kill just about anything known to man in about 5 minutes so more bleach is not better!
What do they know. I've survived a lot more than that, even a few chlorine tank leaks, and I'm still alive a kicking. :D

mmedeiros2
12/31/2008, 06:26 AM
How about filling up with CL2 remover and letting sit when through for some insurance?

AZDesertRat
12/31/2008, 08:41 AM
No need to do that just don't nuke it to begin with, more is not better.

Juruense
12/31/2008, 09:50 AM
I would also disagree with using silicone grease to lube the o-rings aquaman. I have found vegtable oil to be the best choice due to its lack of toxicity and ease of obtaining.

AZDesertRat
12/31/2008, 06:09 PM
I use the edible food grade silicone grease on all o-rings myself.

WaterKeeper
12/31/2008, 07:34 PM
I've always found, when eating o-rings, that they are kind of rubbery. Maybe with some olive oil?