A stronger pump that can flow faster doesn't have anything to do with this either. Two pumps with the same basic flow rate at 0 feet of head pressure can have completely different flows at 4 feet of head. With many canisters once they get the least bit dirty, the pump can no longer push the water up high enough to get anything into the tank, thus stopping all of your bio-filtering, which in turn can cause spikes etc. This problem was very common in the fluval 04 series. A good filter design still would get dirt into the biomedia, because in order for the detritus to avoid the bio-media completely, you would have to have the bio media on a tank without dirt. For a pad to be fine enough to trap all dirt particles, you would be looking at a micron filter pad, which would have to have all the water forced through it. This would dramatically slow the flow of the filter, which would require HUGE intakes to get enough water flowing down to the filter just to get any kind of ridiculously small pump to be fed enough water. It can be done, but it won't be pretty.
