Ro tds ppm

[moumda]

I had my ro water tested and it came up 8.6 ppm tds on a meter our labe at work uses. My domestic water came up 286 ppm. My questions are: Is 8.6 ppm too high (not having a clue what is causing this measurment)? At what level would you recommend I change my ro membrans?

[Randy Holmes-Farley]

TDS in the output is not most useful by itself, as it is a conglomeration of many ions in solution. It is useful for knowing how effective filters are by comparing the input and the output TDS levels

I discuss TDS in detail in this article:

What is TDS?
http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.htm


from it:

". If you are using a TDS or conductivity meter to monitor the performance of an RO membrane, then the measured value should drop by at least a factor of 10 from the starting tap water. So, for example, if the tap water reads 231 ppm, then the RO water should be less than 23 ppm. In many cases, it will drop much more than that. Less of a drop than a factor of 10 indicates a problem with the RO membrane.

8. If you are using a TDS or conductivity meter to monitor the performance of an RO/DI system, then the measured value should drop to near zero. Maybe 0-1 ppm. Higher values indicate that something is not functioning properly, or that the DI resin is becoming saturated and needs replacement. However, that does not necessarily mean that 2 ppm water is not OK to use. But beware that it may begin to rise fairly sharply when the resin becomes saturated. Do not agonize over 1 ppm vs. zero ppm. While pure water has a TDS well below 1 ppm, uncertainties from carbon dioxide in the air (which gets into the water and ionizes to provide some conductivity) and the TDS meter itself may yield results of 1 or 2 ppm even from pure water. "

[moumda]

Thanks Randy. Happy new year.

[Randy Holmes-Farley]

You're welcome.

Happy New Year to you as well. :)