No thermometer needed
I have a beer brewing friend that loans me his digital refractometer for the maple season each year. I make sure he is well supplied with syrup. This one gauge is all we need to almost instantly read sugar content from 0.1 to 85 brix. Two drops is all it takes. I usually take 2 -3 readings with it when I'm pulling off the evaporator and when finishing. So handy as I am running 6 hotel pans and I can get instant readings of where they all are at. Some people disagree on the accuracy of the meter but it has worked very well for me and my syrup has no sugar crystals in it or mold even after sitting on the shelf for 2 years. If my friend didn't borrow me his I would definitely buy my own for $200 as I think it ranks just under a RO for making the process enjoyable.
Dan of Jack & Daniel's syrup.
2021 - First time tapper, 40 TAPS, 7 GAL syrup, 400gpd RO
2022- 105 taps, 17 gal syrup, 2x 400 gpd RO
2023- 143 taps, 27 gal syrup New 12x16 shack. Lost my father in law Jack who helped me build it. New Badgerland filter press.
2024 - 210 taps, 37 gal syrup, 6x 400gpd RO Procon pump