Here's something I did years ago to avoid forgetting to de-tension my bandsaw. I mounted a small microswitch so that the tension lever turned on some work lights when the blade is under tension. The light is not switched with the shop lights. When I leave the shop, I turn off the lights and it's easy to see if the bandsaw blade is under tension. The saw is in sort of a dingy area of the shop so it's easy to remember to tension the blade too. Without the blade under tension, the light's kind of bad.