Dosing the filters with Ammonia!!! Are you sure about that? I have read on forums where people have done water changes and forgot to plug the filter back in and the bacteria has been OK after many hours, I think as long as it stays wet it will last a good while.
only thing is if the filters arent recieving ammonia the bacteria will die off. if you turn a filter off it still has waste in there that will waste away creating ammonia and the cycle continues. when that ammonia is used up, the bacteria dies off, so its questionable how long a filter will last with no power. and as for dosing it with ammonia i dont see ( if done correctly ) how it would be any different from the filter sucking in tank water with ammonia in it, converting to nitrite then nitrate ect and pumping it back out. the key thing is that the bacteria need a consistent supply of ammonia to function. if you cleaned your filter out, got it waste free but left all ceramic rings bio balls containg bacteria and media, everything apart from waste. how long would that filter last without power??