As I stated earlier this is my first time collecting sap from maple trees. As such I have tried to be as observant and inquistitive as possible so I could learn. I have taken regular hydrometer reading and volumes to get a feel for how things "flow". Thus far everything has been pretty steady sugar content wise with an average of 3.5-4 degrees brix. The volume collected each day has certainly been flucuating though. Very much dependent on the temperatures. Some days I get a almost 2 gallons from my 5 taps. One day where it was nice and bitterly cold at night then up into the forties the next day I got 5 gallons!
These observations are all things that are obviously well documented and I have read about or been told directly. However it really makes more sense and I get a better feel experienceing it first hand. Another such observation is the wisdom of removing the frozen sap when collecting. It made sense to me somewhat but I had to test it out. The idea is that you are concentrating the sap collected because the frozen bits are more water than sugar content as water will freeze before the sugar in solution. Makes sense but I had to test it out a couple of times.
My results lead me to the conclusion that while that may very well be important and useful to those making sugar/syrup it was not that important to me making beer. The first time I collected my sap and removed the ice I found the sap with ice removed was about 4.5 brix. So, yeah it was a bit higher. Once the ice had melted and come up to temperature for an accurate reading on my hydrometer (60°F) I measured that as well. It was not completely negligible in my mind. It was about 1.5 Brix. Yes much lower but not completely water. The second time I got similar results, a bit higher at 2 brix. It amounted to 1 quart. So I reduced it for kicks down to 1 pint resulting in a reading of 4.75 brix or 1.016 SG. I then further reduced it to about, oh, 5 TBS! Resulting in 20 brix (1.078 SG) and it was wonderful! Not quite syrup strength but sweet and tasty!