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fiorano
02-28-2009, 02:29 AM
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.
03-01-2009, 01:18 AM
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
03-01-2009, 10:47 PM
the carbon and sediment ones are the first 2 white ones i guess? and alright thanks for the help:)

Myka
03-01-2009, 11:07 PM
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
03-02-2009, 01:15 AM
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
03-02-2009, 01:24 AM
thanks guys ill probably calibrate it anyway just cause i bought it ... and i wanna use it hahaha

fiorano
03-05-2009, 07:13 PM
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
03-05-2009, 08:49 PM
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
03-05-2009, 10:09 PM
think everyone has noticed the TDS increase after being stored for a bit.

Lance
03-05-2009, 11:16 PM
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.

fiorano
03-06-2009, 12:35 AM
ok thanks guys

digital-audiophile
03-06-2009, 02:05 AM
Man, I wish I had 14PPM coming out of my tap!

o.c.d.
03-07-2009, 02:35 PM
I was told or read somewhere that the TDS increases over time because the water is so stripped of everything that is will pull and mix with air. The minute particle in air cause the TDS to rise over time. So all storage water should be in a tightly sealed container.

Myka
03-07-2009, 03:51 PM
Yes, I've found TDS increases quite rapidly in storage. Don't really know why, but it does.

That is because RO/DI water is very "aggressive", it pulls all sorts of crap out of the air very quickly. This is one of the theories behind why many people believe it is detrimental to our health to drink RO water.

Google "RO drinking water bad", or check this out: http://watershed.net/purified.aspx