lots of questions concerning Heat pads and Rheostats...

[megan13]

I recently purchased my first snake, a female ball python. I am looking to buy a heat pad for her as my house is old and gets cold very easily. I know I will need a thermometor/dimmer to control everything, and when I looked up some information, people were saying something about probes? Can someone explain what these probes are, and where should I put them once I get the rheostat? Also when should I keep the heat pad on: day, night, or both? Thank you for your time answering this. I am kind of overwhelmed as to all the different heating options, and figuring out what is best for keeping her the most comfortable. Any advice is welcome!