Welcome to TR, Scienceboy.
I think any of the available digital test kits are reliable by their very nature. I haven't heard anything negative about them. I'm using an old (15 yrs) American Marine, Inc. Pinpoint
pH meter and it works great. It's been in continuous use and I check calibration now and then just to be sure. I usually make a very small adjustment to "zero" it in.
Dick
