yeah, i highly reconmend this piece of equipment. heaters have been know to fail to shut off sometimes, and you could loose your whole tank over a 40 piece of equipment. the ranco will turn the heater at certain temp and turn off when the temp rises to the desired level. if you have a dual ranco, as i do, you can set a chiller or fans to work the same way as a heater- come on when the temp gets too high, shut off when you the temp drops to your desired level. i have my ranco turning on my heaters at 76 and my fans at 78. if the fans are not enough the cool the tank down, my chiller kicks on at 79. my tank generally stays at 77-78 year round.
http://www.rancoetc.com/ranco-etc111000000-digital-temperature-controller-p-86.html
http://www.rancoetc.com/ranco-etc111000000-digital-temperature-controller-p-86.html