Mbu Pufferpedia?

[Myaj]

Exactly. Think about it this way... gross, but it might make you understand the concept.

If someone set up a nice and powerful cannister or power filter on a toilet bowl, even letting it get established and able to "process" the ammonia and nitrates from the waste being routinely deposited.. (mind you, without flushing).. would you still drink that water?

No you probably wouldn't. Not without massive dilution in addition to the filtration. That's what water changes are, dilution. Filtration of the sort we use on fish tanks can only do so much as far as reducing wastes.

Granted, that's out of line with a fish tank in regards to proportion of waste to water volume, but its just as disgusting on the level some fish are made to live in. When dealing with sensitive, scaleless fish like puffers, its definitely a "big deal" to use the most efficient means possible to get wastes out of the water and keep it as clean as possible. When considering the "filters" available to the average aquarist, water changes are by far the most efficient, barring unsuitable water sources (high ammonia/nitrites/nitrates out of the tap for example).