Well, it is possible, but not on the current layout as it has no space available because I was trying to make it as compact as possible. Adding the space for the salinity probe would need reworking the tray layout and overall dimensions, potentially have some wasted space left.
All that being said, if you'd like to go that route, shoot me a PM and we can probably work something out. I would also need measurements for the tester as indont have one on hand to model off of.
Batch dropped off with USPS to go out tonight or tomorrow morning.
Also may be doing a re-design or alternate design for those that want it to incorporate drain holes into the vial cutouts so that you can take the cap off, rinse it out and put the vial in upside down to dry.