On Tue, 12 Sep 2006 19:20:36 -0500, dc wrote:

Dick wrote in
news
It is my observation that filters are actually "strainers." They hold
the larger solids, but the water passing by is eroding the solids and
letting the stuff to return to the tank. Oh, woe is me, I predict
disaster due to negligence.

That's not a strainer, that's just a filter. The primary media traps
debris allowing heterotrophic bacteria (not just flowing water) to
consume it and break it down efficiently into smaller particles which
pass on to the later stages of the filter. Nitrifying bacteria, living
harmoniously with the heterotrophic bacteria, processes the nitrogenous
byproducts of the break down of organic material.

A strainer would be the physical trapping of debris in the absence of
anything else. A diatom filter could be described as an advanced type
of strainer. Any filter that has been broken-in or cycled is not a
simple strainer.


I don't understand much of what you said, but I have 3 different
filters on my 5 tanks. I don't use charcoal and I removed bio wheels,
so my filtration media is a "strainer." What do you believe is
happening to the debris on the media with the water pouring past?

I call it erosion. Works fine, but then I do weekly water changes.

dick
Essentially there are three stages to aquarium filters, mechanical,
biological, and chemical.

Mechanical filtration involves the trapping of physical waste particles.
These are generally the primary and final stages of your filter (that is
if you are using something like polyfiber at the end stage of your
filter to prevent very small particles returning to your aquarium).

Biological involves what I described above. Heterotrophic bacteria
decompose physical organic debris, and nitrifying bacteria go to work on
the byproducts of that decomposition, especially in the later stages
where there water flow is less impeded by the build-up of physical
debris.

Chemical filtration is optional and can involve a wide variety of media
which can trap within them an array of different substances. The most
common types of chemical filtration media are active carbon and Zeolite.