I sometimes need to thin, but that is because I send proper density syrup to my finisher and let it set there until I've gotten enough to fill a barrel or even 2. I then heat it to about 205-210F to filter it, just before filtering I use my Murphy cup to verify the density. I then add pre-syrup off the evaporator or even sometimes permeate to bring the density down.
Adding water, sap, permeate or pre-syrup works fine, but it should not be your go to plan. If you always need to thin it means you boiled too long, using more fuel and along the way you have made darker syrup. I have customers who usually ask for dark, but if your customers prefer amber or golden, you may not get as much of the lighter grades.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.