tds meter

[fiorano]

i just bought one of those tds meters from wal mart everyone is talking about so i figured i should try out my new toy. so the tap water was 14 ppm, our ro drinking unit was 4. and my ro/di was 2... but im under the impression that it is supposed to be 0. My unit has been running for around 8 months... does anything think i should be changing my filters????? can't you tell if the Di needs replacing because it slowly changes color cause only a half inch on the top and the bottom is a light gold color.

[o.c.d.]

First check if the Tds meter is calibrated properly buy using bottled distilled water that should read zero. The you should change your carbon and sediment filters (every 6 months depending on usage and tds reading), Run for 30 min or so then test again. If it is still not down the check DI, many di media change color to a orange when they are exausted. If you do not change the filters regularly your membrane filter will not last as long. That one is the expensive one to replace.

[fiorano]

the carbon and sediment ones are the first 2 white ones i guess? and alright thanks for the help

[Myka]

Check calibration, but don't use distilled water as that isn't accurate. You need to calibrate using solution you buy from an LFS that will be anywhere from 800-1400 ppm depending on brand. That will provide a much more accurate calibration than distilled water.

[midgetwaiter]

Originally Posted by Myka

Check calibration, but don't use distilled water as that isn't accurate. You need to calibrate using solution you buy from an LFS that will be anywhere from 800-1400 ppm depending on brand. That will provide a much more accurate calibration than distilled water.

This might help but I wouldn't bet on it making a big difference, especially if you don't know what standard the TDS pen uses. A TDS meter is s conductivity meter that uses one of several standards to then convert this conductivity measurement to TDS on the display. Depending on the standard used you can get differing results.

Really truly pure water measures about 0.05 mS/cm conductivity. Your average cheap TDS meter can't reliably measure less than 5 mS/cm.

I wouldn't get real excited about 2ppm.

[fiorano]

thanks guys ill probably calibrate it anyway just cause i bought it ... and i wanna use it hahaha

[fiorano]

so the water coming out of the ro/di is 2 ppm and then it was in my mixing bucket for about 4 days and now its up to 27... does anyone else have this problem. could t be something leaching out of the container???

[mike31154]

Might depend on the container, but I doubt it. Is there a powerhead in the mixing container moving the water? How much evaporation do you figure in 4 days? As water evaporates, that would cause any TDS in there to become more concentrated, ergo a higher reading on the TDS meter. I'm just guessing though, I don't have a RODI unit yet.

[mark]

think everyone has noticed the TDS increase after being stored for a bit.

[Lance]

Originally Posted by mark

think everyone has noticed the TDS increase after being stored for a bit.

Yes, I've found TDS increases quite rapidly in storage. Don't really know why, but it does.