Don I take my syrup to where the red line is setting just above the syrup line, I think this is best to be sure of legal density. also I would remind you to wash off syrup each time you check. Syrup will build up on the stem and make it float easier and thus give you a false reading. I have a tall jar of hot water (a thermos works well) by my finisher to swish the hydro in after each test, I also wipe it off after washing. To keep heat in my cup I fill it once with hot test syrup/near syrup hold it for maybe three seconds and dump it back then take another sample and test. I have a homemade copper cup I use and it heats up really fast and retains heat well. With each cup I'd try to check with a thermometer if possible. I'm not sure how well the stainless steel cups pick up and retain heat. I often leave my hydro in clean the hot water or sap then pull it and wipe it off just before testing. I do my best to keep the temps up for hot testing. Cold equipment leads to errors.