Due to a crappy wiring system in my apt. I have all of my filters ect. on my 55 gallon tank on a switch. A light switch. Everybody knows not to turn it off...but one night some bright person I don't know flipped it off and left it off. I'm guessing it was off for about 12-15 hours. No light, no filters, not bubles, no nothing. Evertthing was fine. I'm willing to bet you could leave it all off for days and nothing bad would happen if you have a well cycled tank.