I'm planning on setting up a tank for some FBT's and wanted to ask about water filtration.

I've read that for FBT's, a filter is not essential like it is in an aquarium, but just doing a 25% or 50% water change with dechlor tap water every week or 2, along with wiping down the slime/toxin build up on the sides is enough.


But reading a few posts on here, it seems quite a few FBT setups do have filters in. Is this for bio-filtration (to remove ammonia/nitrate as in an aquarium) or for solid debris filtration.... or both?
I ask because I've also read that the slime coat left in the water by the FBT's blocks up a bio-filter anyway. I imagine an external caninster filter would be a good way to move and filter the water, and could also be used to create a waterfall, but from what I've seen external canister filters are expensive!



So really I just wanted to ask if people do use filters in FBT setups, if bio-filtration (via 'good' bacteria in filter media) is used for FBT's, and probably most importantly what make and model of filter people use that work in such a shallow depth of water - as something like my internal aquarium filter would be far too big!!