Lights Out..

[tlo]

They should recover without any problems. Once the lights come back on tomorrow, they will probably puff up like normal. You probably even killed off some algae with this malfunction.

[Slick Fork]

a 3 day lights out period is actually advocated by many. You'll probably find your sand bed a little cleaner and the water a littler clearer tomorrow. I wouldn't sweat it

[MikeP]

I've wondered about doing a 3 day lights out and have read about the benifits. How would the fish and inverts react to this?

[Slick Fork]

I've done it infrequently and never had a problem with the non-photosynthetic stuff. If you want to try it I would recommend starting out with a 2 day lights off only. See how everything reacts and then if you're comfortable go for that extra day.

Lots of people do it once a month

[Parker]

I do a three day lights out once a month. Like others have mentioned it seems to be beneficial.