74ppt on salinometer!!!
 

So i finally got some clean 35ppt water from the store, and thought finally can move on with the project, but no... i have this digital salinometer, brand new.
When i test its around 74ppt, clearly it needs calibrated, if inunderstand any of this correct? But the screw that I supposed to wind it down to 35ppt, wont go any further down than 74.2ppt 🤔

Have I misunderstood something or what is going on?

Video: https://www.dropbox.com/s/3o2si6usm0...54.07.mp4?dl=0

Ow. I use the other scale, btw. 1.024. Go back to the store and get them to test your water with THEIR instrument, then hand them yours and get them to calibrate it. It's a reasonable service for a new customer.