well I have tested this with my other ph tester and get the same readings with thn both. so it can't be that bad. I noticed though that the battery has to be at full power to work correctly. I do get diferent reading wth different soil. tested that aswell. with both my tests. there is a certain way to use them if used incorrectly you WILL get mix-mached results. use to work at a nusery and this is what they used. I seen one and bought it. either yours was garbage or wasn't calibrated correctly. have you looked at the one that you had and seen the calibration screws in the back? these do need to be adjuste and overall wrk well to get you in the ball park. I basically wanted it for the fertility test so I know when to feed.

so for me it works. but I still need a test for my water.