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Is a TDS meter similar/same as a conductivity tester what you would use for measuring water hardness on aqueriums?

Nope, speaking simply TDS is the total of solids dissolved in the water. Conductivity measures (in this case) the water's ability to conduct electricity. They also use different measurements, TDS uses ppm (parts per million) while Conductivity uses µS (micro-Siemens). Hope this helps!

Mikey3288 wrote:Nope, speaking simply TDS is the total of solids dissolved in the water. Conductivity measures (in this case) the water's ability to conduct electricity. They also use different measurements, TDS uses ppm (parts per million) while Conductivity uses µS (micro-Siemens). Hope this helps!

Actually I'm pretty sure a TDS meter is just a modified conductivity meter. As in it measures the conductivity and uses a conversion factor to give you the PPM reading. This is why a TDS meter won't indicate if there are non-ionic dissolved solids like sugar.

Edit: Here is a good easy description on what a TDS meter really does.

http://www.reefkeeping.com/issues/2004-04/rhf/feature/

Ahhh very interesting read. I didn't know how TDS meters actually worked, just what they measured. Didn't want to pass off bum advice, thanks for the correction

Mikey3288 wrote:Ahhh very interesting read. I didn't know how TDS meters actually worked, just what they measured. Didn't want to pass off bum advice, thanks for the correction

No problem. I've given my fair share of bad advice before.