Do you have a meter that can measure EH that you might recommend? I know they are effectively useless for soil but there are some water based things I wouldn't mind getting a grasp on what is going on with on that side of things. E.g some of these sprays and the biodynamic 501 prep with the quartz.
Discussion
I just scooped this one up from Ebay a few months ago for a good price, I do need to order calibration solution to make sure it's accurate though. 
I was gifted one of these Hanna meters (Hanna Groline HI9814) and it does pH, ORP reading + temp.

It's a more expensive model but seems to do the trick for measurements.
Though I should get some more calibration solution and make sure its still in check. 🤔
If you could use the HM Digital model I have, let me know.