I use W/Ds or canisters on my planted tanks without any problems. It drives me mad that folk say that filters "compete" with plants for ammonia. In a low bioload heavily planted tank there should in theory never be a detectable ammonia reading. I am not willing to take that chance, so I use filters. My tanks are almost all moderately lighted, so whether or not I ever get any nitrate reading fluctuates from tank to tank - many do show some nitrate, so on those at least I know that i need a biofilter.
Because I always multi-filter every tank, I am accustomed to 'stealing' in-use filters for other tanks being started. This is no issue from FO tanks, but the canisters stolen from planted tanks are well inoculated but not "mature" - they cycle quickly but they do cycle at barely detectable levels. Ditto for bioballs lifted from one tower to start back up another which had been idle a few months. To me this indicates that rather than the popular myth, the plants out-compete the filters.
Bacterial blooms in the water have nothing to do nitrification. Those are from heterotrophic bacteria, not the nitrifiers. If they required attachment as nitrifiers do, they would not, could not, be loose in the water column causing a bloom. Completely independent of biofiltration bacteria.
The biggest issue of W/Ds on planted tanks is whether or not your overflow blows off CO2 - some do, some don't. the tower itself rarely does if a decent commercial unit.
HTH
