changing RODI filters

[Mando77]

I have an AWI RODI unit (150 Per Day) and I have not changed the filters in over 2 years, but both of my handheld TDS meters read 2 PPM. Should I change filters because of age, is there any side effects of leaving them in to long?

[Quantum Aquaria]

i'm in the same boat... i run mine to death for 2 years now... was thinking about replacing the filters, but since i couldn't locate my handheld TDS monitor, I ordered an inline one from BRS, hooked it up and it reads 0

 

turned it off, back on... 0

 

not sure what the deal is, but there is no way that all my filters are so good that I have 0 TDS

[GraffitiSpotCorals]

I an inline Tds meter and it won't even calibrate it's junk. And hm is retarded called multiple times and they just keep giving me stupid advice so i concider it money lost. You both haven't even changed the prefilters in two years??? Or just haven't changed the Ro filter?

[Jon Lazar]

Put the electrode in some tap water and see if you get a non zero reading.

[GraffitiSpotCorals]

I meant to say I bought an inline Tds meter...

[Mando77]

I also have a inline TDS meter. Ive tested the hand held meters and they work. I haven't changed any of the filters in 2 years. But I only use about 100 gallons a month. I just was told by AWI to change out filters every year, but I didnt see any reason to because my water was still very good. You can see my filters, they still look as clean as the day I bought them 2 years ago?

[Dholmblad]

Wouldnt it really depend on the TDS coming into the RODI unit

[GraffitiSpotCorals]

If that's true I want the same unit! I change mine out often because when I first got it I didn't know you needed to change them out every few months and I went one year, the whole thing was brown and barley putting out water. Tds was like 50 or 60 from what I remember. Hard to believe yours would still be running well after 2 years! How often do you change your di resin?

[Mando77]

I have never changed out anything since I bought the unit. I'm guessing my water going into the RODI unit must be pretty good. I bought the unit knowing I would have a larger tank, it is over kill for what I have. I still would expect to change filters more often or have water that would get worse over time. Haven't noticed a difference really. It was at 0 TDS inline for about a year now around 2 TDS. I can tolerate that. I was going to change out once it got around 5, but I don't know when that is going to come.

[extreme_tooth_decay]

I have always thought that the prefilters do not effect TDS, only the membrane (though it seems like the sediment filter should, the carbon filter removes chemicals and contaminants like chlorine that do not show up as TDS because they are not solids).

 

I change mine every 6 months, or when the sediment filters looks nasty-yellow, which is usually about 6 months.

Edited April 9, 2012 by extreme_tooth_decay

[Jon Lazar]

Here's my understanding of how these systems work:

 

Sediment filter protects the carbon filter.

Carbon filter protects the RO membrane from chlorine damage.

RO mebrane filter removes nearly all of the TDS.

DI removes the remaining TDS.

 

Theoretically, you could run city water through just an RO filter with no prefilters, and achieve the same filtration for a while, but chlorine and sediment would damage the RO membrane.

 

You could also run just DI and get 100% filtration, but you'd go through lots of expensive DI resin.

 

I change my sediment filters when they get too brown, or if the pressure gets too low. They're cheap enough that I buy extras whenever I order something else online.

[STEVE]

I'm sure it depends on the local water authority...Manassas, Prince William, Fairfax, etc

[extreme_tooth_decay]

I'm sure it depends on the local water authority...Manassas, Prince William, Fairfax, etc

 

I'm sure they all have chlorine in them...obviously could be in different concentrations.

 

To me the prefilters are cheap enough that I just replace them periodically.

 

I also think the carbon is removing many other contaminants besides chlorine. Carbon is great stuff and should be replaced to maintain its effectiveness.

Edited April 9, 2012 by extreme_tooth_decay

[ErikS]

I'm sure they all have chlorine in them...obviously could be in different concentrations.

 

To me the prefilters are cheap enough that I just replace them periodically.

Might even depend on the part of the county - in my part of PW county the water comes from the Faifax treament plant (Occoquan). Also depends on the time of year - this time of year they often turn off the ammonia pumps = clorine & not cloramine.

 

Depends on the carbon, some are better @ removing Clorine, some @ cloramine..........given carbon is cheap & membranes are not?

 

But then I'm lucky - water starts off @ a low TDS, my filters last quite some time.

Edited April 10, 2012 by ErikS

[STEVE]

It seems like they all tend to be changed at different times, there is no "set" time to change them.I watch my TDS and coloration, when it gets to 2ppm on the output, I change them. If there is a better way, I'm open to hear it.

[extreme_tooth_decay]

It seems like they all tend to be changed at different times, there is no "set" time to change them.I watch my TDS and coloration, when it gets to 2ppm on the output, I change them. If there is a better way, I'm open to hear it.

 

Watching the TDS is not of any use, because the prefilters do not effect it in any significant amount (if at all).

[STEVE]

.......I agree the TDS has nothing to do with the prefilters, I was just saying for overall health of the RO DI system, but your 100% correct, sorry for the confusion....thats why I said I watch the color aswell.

[Ryan S]

 

Relevant to Chloramine discussion. Just posted recently.

Edited April 10, 2012 by Ryan S

[zygote2k]

I've read extensively on this subject- I change the prefilters first, then the carbon, then DI resin in that order when TDS out is greater than 10% of TDS in. This method has worked for me on many systems. As far as lifespan of cartridges, I can believe that 2 years on all of the cartridges is fair since I've run my home system for about that length of time before changing them.