TDS Readings

[robertfah]

Hi all,

I an AquaFX RO unit and haven't changed the filters in a LONG time....but my TDS readings are saying 0 for out and 200 for in.....that's still good right? What is everyone else getting for readings?

[neilanh]

I can't get to 0TDS, and it irks me. I hold steady at 4 and can't get any lower. My input is between 160 and 200.

[robertfah]

Originally Posted by neilanh

I can't get to 0TDS, and it irks me. I hold steady at 4 and can't get any lower. My input is between 160 and 200.

Mine is going through a Rain Soft system before hitting the RO, so that is probably helping a lot.

[Kurt_Nelson]

neilanh... add a DI stage and you should get to 0. I'm guessing you're running just RO? With a DI stage, there's no reason you shouldn't get to 0. Unless the DI resin is depleted.

To answer the original question... I agree - 0 is 0, so I'd say it's good. Have you double checked the calibration of your TDS meter?

[robertfah]

Originally Posted by Kurt_Nelson

neilanh... add a DI stage and you should get to 0. I'm guessing you're running just RO? With a DI stage, there's no reason you shouldn't get to 0. Unless the DI resin is depleted.

To answer the original question... I agree - 0 is 0, so I'd say it's good. Have you double checked the calibration of your TDS meter?

no.....but I'm guessing any LFS would be able to help me with that?

[neilanh]

Thanks Kurt, but there is a DI stage on my unit. THe unit isn't even 4 months old yet, and I've never gotten it to 0TDS. It's a 6-stage system that I got off of ebay.

[Kurt_Nelson]

Originally Posted by neilanh

Thanks Kurt, but there is a DI stage on my unit. THe unit isn't even 4 months old yet, and I've never gotten it to 0TDS. It's a 6-stage system that I got off of ebay.

Hmmm... I'd be willing to bet that the original DI resin that came with your unit might have been depleted to start with. When DI resin is exposed to air, it loses it's capacity pretty quick. If the resin wasn't sealed, it might not have been very good right out of the box.

Only reason I say this is because I use straight DI (no RO) to purify my water and I can get my water down to 0ppm with no problem - even flowing at 60 gallons/hour (that's HOURS... not days). So if you're trickling it through an RO to start with, the DI should have no problem stripping whatever is left down to 0. Or perhaps the TDS meter is out of whack.

robertfah... you should be able to pick up some calibration solution somewhere if you want to double check your meter. If your LFS doesn't carry it, then try DrFosterSmith, PremiumAquatics, MarineDepot, or any of the other big online folks.

[CaptainAhab]

Possibly the DI resin isn't/wasn't packed tight enough and you have some channeling going on. If you bought some extra you can tamp it down and repack, of just try tamping down what you have.

[robertfah]

Originally Posted by Kurt_Nelson

robertfah... you should be able to pick up some calibration solution somewhere if you want to double check your meter. If your LFS doesn't carry it, then try DrFosterSmith, PremiumAquatics, MarineDepot, or any of the other big online folks.

Thanks Kurt....I'll look into it. It'll be interesting to see if it's calibrated correctly or not.

[neilanh]

Thanks for all the advice. I did notice when I got the unit that the resin wasn't packed in very well, so I ordered more and really packed it in there, that's what got me down to 4, I was up in the 20s.

I didn't know exposure to air would deplete the resin. I have a small bag that hasn't been sealed sitting here I was pondering replacing it with, but since it wasn't sealed I guess I should order a new bag.

[CaptainAhab]

also keep it out of the sunlight..

You might have some channeling going on the packing won't solve. If you really want to try to get to 0 it might be worthwhile to replace all and repack. Assuming that your TDS is calibrated correctly of course