If its just the lower leaves, it could be as simple as lack of light through the canopy. 2 or 4 isnt a big deal, Its bad when you start loosing 6 or 8 at a time. As for keeping night temps a little higher, id be no use there. Adding heaters is a hassle but also building a enclosure is a hassle. Ive been lucky and stayed away from concrete flooring. I think you're doing perfectly fine though and she looks good from your pictures. Keep doing what your doing and youll be fine. Im the same way when it comes to my comments, everything i type sounds mean to me but i mean it whole heartily in the nicest way. If you do start a journal or start another thread, let me know.