My FX5 died, and it's not the first time I've heard of them just not coming back on after you unplug them to clean them. I think it has something to do with the internal computer. It eventually came back to life. However, if we didn't have 2 other canisters (xp3 and xp4's) on that tank, we would have been in big trouble. Out of the filters we have (marineland canisters and rena canisters, plus the FX5) this is the only one that's ever died like that. I wouldn't trust just one. 2 sounds like a much better idea.