TDS meter in freshwater tank?

[BigTruck6o2]

I know a TDS meter wont work in a saltwater tank because it messes up the reading. If i stuck my TDS meter in my freshwater tank that would work right? I just did it to one of ours and it came out at 421...Is that an accurate reading if my RO it comming out at 0? Basically i want to know if a TDS meter will work in a freshwater aquarium.

 

[BrianNY]

I use a TDS meter for my discus tanks. It works just fine. You have to realize that there are other factors contributing to TDS in your aquarium besides the water. How frequently and how much water you change will affect the reading.