Today we had a power cut, first time in the 2 years our house has been built, only for about an hour which wasn't too bad but it did seem to be the longest hour of my life as I sat staring at my tank. (first day off work in 2 weeks and I can't make a cup of tea, watch jeremy Kyle ect all the important day off stuff!) All turned out well, but it got me thinking what to do if the power ever went off for longer, maybe for most of the day, about 7 -8 hours? or throughout the night when I wouldn't even know it had happened until I woke up 3 hours late for work because the alarm clock would have reset itself to 00:00 and erased my 6am wake up call (as they do, and nobody believes you! ) So the question is; how long will a tank keep stable conditions with no effect to water conditions without being filtered? (230l, ext filter) maybe internal filters will be different because the tank water is still in contact with the filter but of course if an external stops working then there's no filteration at all. Has anyone had long power cuts and had problems with their tank because of it? What can I do to help the situation?