RO/DI question

[drock59]

I just bought a six stage RO/DI unit. The last stage of the unit is a GAC(granulated activated carbon) and has a TDS of 1-2 but when i test water before the GAC it has a tds of 0. Should I be worried about this?

Is the GAC adding some particulates back to the water? I thought it might just be the meter but why would it read less TDS on supposedly less pure water?

[Chief]

I took my carbon off of my RO/DI unit to avoid this. My water tastes just fine even though I am not using the last stage of carbon. For what it is worth, I even took off the DI chamber. I was getting 0 TDS after the RO membrane, and after over a year, I am still getting a 0 TDS reading. My water starts out as only a 27 TDS so I guess I am just lucky.

Jay

[rong666]

You probably need to flush out the GAC for a good hour to blast out all the fine particulate carbon, after that, you should get a tds reading of 0. This worked for me
-Ron

[drock59]

Thanks, Ill try and blast if it doesnt work out it goes.

[impur]

Which unit did you get? Just curious.

[drock59]

aqua safe maximus 100gpd with the storage tank.

Cranks out a fair amount of water.

[impur]

Nice. I'm going to upgrading my Filter Direct unit with a better RO membrane and larger DI canister.

[drock59]

Miles, I am thinking of mounting my DI cartridge vertically also. I have read that it prevents "channeling" but I am not sure if it is necessary. I feel a lot more comfortable with the RO/DI unit even though my TDS out of the tap is something like 65.

[parvo99]

I have the same unit, and I get also get a reading of 1-2 after the final gac, and 0 before it. It's still the same after several hundred gallons. My tap only measures 14.

[drock59]

That is really annoying... im sure aqua safe knows about this issue. Isnt the whole point to have 0tds? Regardless, ill just take off the GAC, no big deal.

[impur]

You know, RO water is real touchy. If you make a batch of water at 0TDS and leave it uncovered, say overnight, you will get a TDS reading the next day. Heck you can change the pH of it by blowing across the surface. I'd say anything below 5ppm is close enough.

[Krux]

I had that problem, it took about 6 months for the tds to drop to 0, and it has been at 0 for over a year now on the first set of cartridges (and i like an idiot bought a case so i have like 15 years worth of filters). I guess since my tds out of the tap is 14, i really didnt need the 6 stage, but it was only a few dollars more, and now it makes water nicely for me.

i would test your water for phosphates and nitrates, carbon isnt going to remove those. if you are at 0 for both of those, then you can probably safely pull out the carbon, unless you are on a well. If you use well water you are going to want to maintain the carbon as there are other trace elements in well water that really you dont want, and it is worth 2 tds to get them out.

as posted above though, if you are under 5 you are doing good, so i wouldn't worry too much either way, personal preference at this point once you have tested the above stuff.