Conductivity meter vs TDS meter

naptalene · Oct 9, 2017

Hi,

First off, I have some kit that I bought from a friend.One of the units is a conductivity unit for my ReefAngel. I am not that bothered about having this metered, but if it's available, its a great addition to have.
There is a good chance that I might need to replace the probe so I was online looking for some. I then the BRS video on TDS. They state that it's basically measuring conductivity and doing some maths to convert the reading to a TDS value........ so why aren't we all running tds meters in our tanks to have a birds-eye view of conductivity = salinity? Surely you could calibrate a refractometer, get your salinity to the value you want and then use a tds probe as a real-time monitor? Even if the numbers are irrelevant, you know that you should read a value of X on the TDS meter for a given value on your calibrated refractometer (or hydrometer for that matter)

Am I missing something or are we missing a cheap trick that could be a quick, relatively cheap indicator for the onset of salinity issues. Could be great for Nano's?

Disclaimer - It's normally a case of Me mis-understanding something

Randy Holmes-Farley · Oct 9, 2017

The main reason typical TDS meters sold to hobbyists cannot be used for salinity in most cases is simply they do not have the dynamic range to read all the way up to seawater TDS. That's why, for example, Pinpoint makes two nearly identical meters, one for low values like RO/DI and one for high values like seawater salinity.

They can be made (I have one and we have recently been discussing them in the chemistry forum) to read both low TDS for RO/DI and high TDS for seawater, but are much more expensive.

https://www.reef2reef.com/threads/conductivity-meters-pinpoint-vs-used-lab-grade-units.327201/