Surely even the most balanced setup cannot last indefinitely.....
There comes a time in the life of every tank when it becomes necessary to do a complete springclean.... (remove the fish, remove & wash the gravel, take the tank outside & wash the glass, etc. etc.
What are the indicators and does it vary with the size of the tank.....
The longest period that I've kept a tank going was around 5 years with no intervention.... (4ft setup)
(obviously, apart from water changes, glass scraping & gravel siphoning)
There comes a time in the life of every tank when it becomes necessary to do a complete springclean.... (remove the fish, remove & wash the gravel, take the tank outside & wash the glass, etc. etc.
What are the indicators and does it vary with the size of the tank.....
The longest period that I've kept a tank going was around 5 years with no intervention.... (4ft setup)
(obviously, apart from water changes, glass scraping & gravel siphoning)
With UGF, 1 year is about adverage. I've never had to strip a tank running an internal, exturnal or sump filters however 
With UFG, the flow drops off and you cannot clear the clogg with gravel-cleans of reversing flow. This is when the plate itself has clogged and needs, more direct 
, attention from below...
