One of the most important aspect in all we do; environmental engineering, home building, and even just taking a hike locally; is personal safety.
A real, cut Christmas tree has so many benefits. It will, not might, be very dangerous when dried out, wrapped in a heater (lights), near an open fire or candles.
So google Christmas tree fireproofing and check out the posting to make a solution to water your tree and keep your family safe. The one you want is put up by a state emergency response person.
It lists the ingredients, borax, karo syrup, Epsom salts, chelated iron, bleach, and water. It also gives a great narrative describing how each ingredient contributes to the fireproofing.
I used this in the past and it is pure magic. Also it keeps the needles on the tree for a much easier clean up, and the tree smells awesome.
Just a quick disclaimer: use at your own risk. Be careful to not spill as the iron makes the solution blood red. On a legal note, Ramon from the legal department suggested I remind folks you agree to hold me harmless from responsibility for your use of this awesome advice.
Wishing you all a safe and happy holiday season. Randy