The room in which I would like to have my tank for axolotls (my bedroom) when I get them is pretty cold during the winter, on average 60F (15.5C) for most of the winter but night drops are about 55F (12.7C). Is the day to night fluctuation so much it may stress an axie out? Also since my average temps for the day in the winter are what I have read to be in the lower comfort range of an axie should I try and raise the water temperature somehow? Lastly because of this should I try to find adults or when I am ready? I am planning on setting up either a 55 gallon or a 75 gallon as I have both empty currently. Thanks for any and all help.