TDS Meters

[RayAllen3422]

So I bought a handheld HM TDS meter to verify my HM inline meter was correct. One said 10-11 TDS and one said 0 TDS. This was there response:

These meters are accurate within 2%, but have a range of 500ppm TDS, meaning 10ppm TDS is within that range of error.

Then they told me to buy calibration solution and re-calibrate both. I have had the RODI with the inline meter 3.5 months and the handheld one 1 week. Has anyone else had this issue?

[bertoni]

Oh, sigh, that's one of the problems with hobbyist equipment. It's difficult to get enough accuracy for some parameters. The Oakton EcoTestr low range meter allegedly is more precise, but it's running about $65.

[disc1]

When you use the handheld meter I assume you are putting the water into some sort of container. That container must be immaculately clean or whatever is in there will show up. And even when it is perfectly clean some CO2 will dissolve into the water and that will register a few ppm.

[bertoni]

Another good point. The samples are easy to contaminate.

[Buckeye Hydro]

At least half the time when we field customer service phone calls on this topic, the issue ends up being "user error." Dirty sample containers being a prime example.