Help with RO/DI

[wetone]

I recently had a failure with my RO/DI autoshutoff unit...my system was running waste water constantly for a month and my TDS was way up there, all my membranes/cartridges were replaced only 6 weeks before ($$ out the window !!). I talked to someone who said that the DI unit does not get water passed when the product water is shut off, even though waste water still flows.
So I only replaced the RO cartridge. I did not change pre, carbon or DI......that was only 11 days ago. I now have a TDS reading of 56 !!!
I have replaced the auto shutoff, so I know the system is shutting off when the top off tank is full.
The obvius seems to be that the DI and other filters need to be replaced, but I'm just looking for some thoughts.
My tap water is around 175.
Does the DI cartridge bring the total TDS down that much? I know my TDS should be near 0 at only 11 days into a new RO cartridge.
Also, I have a TDS meter that says it was factory calibrated and I dont see anything on it to adjust now.....what can I use to test the TDS meter??

any help/thoughts from some water experts is appreciated

 

[Roy G. Biv]

From what I understand.,, The prefilters dont do much for TDS. They just take out large crap, chlorine etc.. The RO should knock the TDS down to 5-6 and the DI should take it down to 0. I think if the TDS is 56 before the DI, you will exhaust it very quickly.

IMO its the RO that is shot if it is passing 56 TDS. You can try doing a MAJOR flush on it if your setup has it.

 

[wetone]

I do have a flush kit....I will try that..

Any ideas how an RO can get that depleted in only 11 days??/ something has to be wrong

 

[IslandCrow]

The TDS of my tap water is just about as high as yours, and with a new RO filter, the TDS is between 0 and 1 before it gets to the DI membrane. In other words, I think you definitely have a problem somewhere prior to the DI, and probably prior to the RO. Make sure your cartridge is seated properly. The prefilters will reduce your TDS. The carbon not so much, but the micron filter will. My guess is that the water is not flowing through your RO membrane properly. Unless your membrane was just bad to begin with, I doubt that it's shot.

 

[fatboyjoe]

is your wase water still flowing constantly?

 

[wetone]

no..the waste water has stopped ..althought the shutoff solenoid makes a strange humming/vibration noise for about 3-4 seconds every few minutes. The tech support people at Kent think there was an air leak, so I tightened all the nuts, but it still does it. Not sure if there is a faulty solenoid or not.
I wil open up the unit and check the RO to see if it is installed properly...

this unit has been working for 5 + years with regular filter changes, so I'm not sure whats happening yet

 

[fatboyjoe]

just for the hell of it, check you check valve, mine went on me after 3 years, it's either in-line or attached to you r.o. housing. take it off and blow into it, you should only be able to blow through it one way.this could cause all kinds of problems.

 

[rbursek]

Let the ro run for about 15min to get any tds creep out before you test it.

 

[IslandCrow]

If you're not getting any waste water, I think that's more evidence that the water is not passing through your RO filter properly. The RO filter should be rejecting some of the water that's trying to pass through it.

 

[AZDesertRat]

What is your tap water TDS, RO only TDS before DI and finally RO/DI TDS? You need all three of those numbers to troubleshoot the system. How are you taking the TDS readings and is the meter and glass or whatever you are testing in clean? Are you testing directly out of the unit and not from a tank or holding vessel?

 

[wetone]

Well I shut the system down and pulled out the check valve on the output of the RO cartridge, it seemd OK. I then pulled out the RO filter and reset it in the cannnister. I checked all the fittings, the flow restrictor and turned it back on.
My squeaking noise which seemed like a "pressure leak" has stopped and after a major RO flush and running some water my TDS has dropped to 2 !!!!:eek1:
I assume that the RO filter was not inserted properly in the cannister and unfiltered water was passing by (good call islandcrow!!)
I have been metering TDS via an inline meter that measures both tap and product water. I also have a handheld meter that I take water directly from the product side into a new clean plastic cup....bot readings are pretty much the same now

thanks for the help