His day and night cycle is 12 hours. Light are on 9:30 a.m to 9:30 p.m. I did clean out there tank about 2 weeks ago. Everytime I do I always make it look different, rearrange stuff. He has always been fine with this. The only change that I can think of is that I run a night time bulb now because of weather starting to get cold. I run a incadesent bulb for heat purposes. Like I said looks fine just hasn't moved from the same spot in about a week.