We use the EISCO potometer with a few adaptations:
1. permanently fix the clips with screws and glue (instead of the pathetic two sided tape)
This makes everything more robust
2. Remove the 5ml syringe and replace with a 100ml reservoir
This improves the machine by allowing you to feed the plant off the reservoir and I have set it up and left it all weekend - still works on the Monday morning (all be it a bit slower due to the stem getting blocked by infection).
3. Everything fixed on one clamp stand
Kit taped down, top clamp gently holding the plant second clamp holding the reservoir. The whole set up then can be easily transported to different locations.
Use the tap to control what you are doing . - in line for running, top and right to feed off reservoir, right and bottom to zero the capillary tube (using the liquid from the reservoir with care)
The good thing about the EISCO is you can remove the tube connector and fix it on the stem under water without any Vaseline or vacuum grease just cut it at an angle, push on to one end then seal with several twists of elastic band. Join up to machine under water. I use laurel because the stems are the right size are woody so they push into the tube easily and are evergreen so you do this at any time of year