WTF... RO/DI putting out high TDS!!! help please...

[jandree22]

So I just ordered new sediment, carbon, and di cartridges for $60 shipped from AirWaterIce.com and I'm getting ready to change them tonight. But, before I change them, I test the TDS of my tap water and what the unit's currently putting out... tap water about 250... RO/DI about 60!!!

Even with exhausted cartridges, shouldnt the membrane still be lowering it to <10-15?! I wanna get these changed, but no use exhausting the DI if the membrane isn't working. If I have to spend another $60 for a new membrane yet... this RO/DI has been nothing but problems!!! :evil:

What you guys think, need a new membrane?!

 

[FragMaster]

I would say thats the culprit. How often do you use it? If youdont use it more than once a month your gonna get high TDS readings because bacteria will start growing in the membrane.

 

[rayman]

i agree with fragmaster, i have read a bunch on the subject a few months back, and what i recall is even if i'm not using it often run it a few hours a week or so to clean out the membranes

 

[trigger0214]

Did you sanitze the system when you installed the new filters? You should be able to run some hydrogen peroxide through there with no damage to the TF membrane.

 

[jandree22]

Did you sanitze the system when you installed the new filters? You should be able to run some hydrogen peroxide through there with no damage to the TF membrane.

Nope, sure didn't sanitize. How the heck do you get H2O2 through the membrane... specifically, how do you pressure it?

I guess it'd be a big no-no to give it a quick shot of straight chlorinated tap water to kill the bacteria, wouldn't it?

 

[jandree22]

Fck it... I decided I can't twiddle my thumbs over this any longer, the algae problem in my tank is too advanced to put it off. I just ordered a new membrane. Oh well... I'll just take better care of it this time around :wink:

 

[FragMaster]

:wink:

 

[Anonymous]

You need to go thru the system with a good TDS meter to troubleshoot if you still have problem. Sanitizing it does not give you better water, so it si something else. Good luck.

 

[jandree22]

Speaking of TDS for a minute... what's the best method to test the water. I find that it's easiest to test when the water is in a container and I just stick the meter in, but I also find that any container will hold residue from previous fluid. Is the answer to this to just use a new plastic cup every time I wanna test the water? I tried Dixie cups last night, but determined that they're giving off some kinda residue. And running the sensors under flowing water makes the reading kinda jump all over the place depending how perfectly it's hitting it.

Maybe if I just get some of those knock off plastic dixie cups rather than the waxed paper ones, that would work accurately?

 

[Anonymous]

I just use a coffee cup and rinse it and dry it thouroughly. I always get 0 reading when I do that.

 

[jandree22]

I just use a coffee cup and rinse it and dry it thouroughly. I always get 0 reading when I do that.

easy enough... thanks

 

[Anonymous]

I use a small glass tumbler and wipe it down good with a towel before and after. - I use this same glass for preparing food mixes, dosing, FW dips, etc...

Glass is far less likely to carry anything over.

 

[Anonymous]

Or yeah, coffee cup works too..

 

[Anonymous]

Just wash the container several times if you are picky. Reading usually goes lower after a rinse or two. For RO/DI, reading should not change much if the water is flowing thru the sensor. Either you have air bubble issue, or there is something wrong with the meter.

 

[Anonymous]

Your unit should have a back flush valve that runs water backward and spits it all out as waste water. You should flush the system out like this for one hour at least twice a month to keep it clean.


Sometimes, if your original TDS is very high, the filters give out a lot faster because they get full of the dissolved solids. My starting TDS is about 40 and water comes out of my unit at under 5. I bet if my source water was 250, the water out of my unit would come out a lot higher than 5.

 

[jandree22]

I occasionally flush it, but not nearly an hour twice a month!!! 8O

I'll def do it more this time around

 

[Anonymous]

>...Even with exhausted cartridges, shouldnt the membrane still be lowering it to <10-15?!

When the DI get to the end of it life, it actually can release some of the ions that it caught long time ago, making the "DI'ed" water to have a higher TDS reading than the input water.

As I said, you need to do some debuging with a good TDS meter if you really want to know why. Can save you money since you may end up throwing a good membrane out if you does not test it.

 

[jandree22]

Well, the think that baffles me about the DI is that it’s a color changing DI (dark green to bronze). It’s bronze about 3/8 of the way up and the rest is green. Stupid me, I assume that should mean it’s only 3/8 exhausted, but like I said, stupid me to assume such a foolish thing… :roll:

Tonight I’ll test the water straight out of the membrane before it hits the DI to see what number I get. Thanks for your help…

 

[Anonymous]

My RO does not have a back flush on it? Is that really neccesary?
_________________
Honda VFR400

 

[Anonymous]

I occasionally flush it, but not nearly an hour twice a month!!! 8O

I'll def do it more this time around

I got my RO unit direct from a manufacturer. Because I had a shut off valve problem due to extremely high water pressure in my pipes, he had to send me a special valve. In talking to him a few times over the phone, he told me that flushing an RO unit twice a month will increase the life of the unit by a great deal. Also, he said that a proper back flush should be for between half an hour to an hour and that anything less would not do as good a job.


I trust his advice and my 2+ year old unit still turns out very clean water with single digit TDS readings.