Hey Dr. G. Here is a man that what to do with his probe Byron << Last spring someone mentioned they used a <<used water bed heater for starting seeds. <<Where did you put the probe aka temp sensor? >> <<I don't remember if I made the original post, but I <<also use an old water bed <<heater. I use a seed starter kit with a plastic tray, <<cell packs for <<planting the seeds and a clear cover. I just put <<the probe at the bottom of <<the tray between the cell pack cells in the center <<and put on the cover as <<best as I can with the probe wire running under <<it. If you're using <<individual pots or cell packs, try putting it under <<whatever container you <<use. You may need to use something else as a <<spacer under the container to <<keep it level.