How accurate are TDS Meters?

[J and S]

Ok so I have 3 of the popular TDS3 ppm testers.

I splashed out on some calibration fluid and all 3 failed.

The newest is about 60 out the oldest about 80 both above what they should read.

The other one is about 60 below what it should read.

Only the oldest has an adjustment screw but it doesn't seem to work very well.

So how do we know what our pure readings really are.

In all fairness I got talking to another wfp user about 6 weeks ago and we tested my water using his meter and mine and they both agreed on 2.

 

[Skxawng]

The margin for calibration error seems to be higher depending on the reading. With low readings like <10 they seem a lot more accurate. Its always good to have two in agreement though in case.

 

[J and S]

Sort of defeats the object of calibration fluid though doesn't it....the fluid is 342ppm.

And no way of adjusting the calibration doesn't help.

 

[KWClean]

If there is no way of adjusting for calibration it is junk.  Might sound harsh, but it is the truth.  Have any of your meters got a facility to adjust for calibration?

The fake ones you can not calibrate, the real ones you can. 

 

[J and S]

Yes my old one has but it doesn't actually do anything....all 3 are from PF.