most important thing to remember with any electronic tester is to get one of good quality, as far as the readings it shoul have its simple
an EC meter needs to read from0{duh} to around three or 4.0 cf
its the range you will be working in. all comercially available testers work within those ranges
there are beter than others, it always to pay a little extra fo a water proof one, again it always pays to pay a little more for one that auto calibrates and reads temp of sollution!,,, you could always buy a combi that does all this and EC !.... although i like to keep a seperate EC and PH tester, as if one goes i dont loose all control!.
Hanna are good , i have used them for many yrs
ythe combo does EC PH SAL TEMP
or a simpler version for around 50 to 55 euros does EC or PH
try not to buy too cheap! and remember tpo buy calibration fluid and test every week!! the better quality and more expensive the longer it will last! but they are all very sensitive and even the smallest of drops means a re calibration to make sure, nothing worse than working with confidence with a baddly calibrated ph or ec meter,,,,,,
good luck