Understanding How Aquarium Filtration Works

Aquarium filtration is vital to an aquarium’s success. If you want your fish to thrive and be healthy, then you have to make sure that your filtration is top-notch and working just fine.

However, just what is aquarium filtration all about?

Most people think that filtration is just about sticking in some sort of machine inside the aquarium and cleaning it once every other week. At the same time, you’ll need to do more to make sure that your fish stay healthy.

Mechanical Filtration – This is what most of us see when we look at a typical aquarium: a mechanical pump that sucks water, screens it using some fine material or cloth to sift the water, and then releases that water back into the tank to aerate the water. The finer the filter material, the more effective it is at filtering but the more quickly it gets clogged up. So unless you have some serious waste problems in your tank try and find a filter screen that strikes a balance between efficiency and permeability.

Mechanical aquarium filtration serves to filter out the solid particles like waste and grit from the water. This in itself is important, and definitely cannot be overlooked in your tank’s cleanliness. But not all problems in an aquarium are visible; some are hidden to the eye.

Water, especially water that comes from the tap, has certain compounds that get dissolved in it. These compounds accumulate over time, as they cannot be filtered by mechanical means, and have the potential to kill your fish once they reach toxic-enough levels.

Chemical aquarium filtration involves using high-grade ‘granular activated carbon’ to absorb these dissolved compounds. Certain materials are super-heated at 2000-degrees Fahrenheit, and the resulting material is then void of gases due to the super-heating process. Since the material doesn’t contain gases, it absorbs the invisible compounds, much like sponges do.

But these carbons will eventually become saturated with compounds, needing replacement. Activated carbon is more effective than charcoal in absorbing the compounds mentioned, contrary to what some aquarium shops will tell you.

Biological Filtration – As your fish go about the business of living their day-to-day lives, the respiration and waste-production process will produce a certain substance: ammonia. This ammonia, which also comes from decaying matter, is very toxic to fish when it builds up long enough in your tank, and is the most-often overlooked of all the filtration types.

In order to deconstruct the ammonia that can be found in aquariums into benign nitrate , biological chemical filtration is necessary. Nitrosomonas are a species of bacteria that turn the ammonia into nitrite. This nitrite is still toxic to fish, and it has to be processed by Nitrobacter bacteria to produce the nitrate.

The lack of these bacteria is the entire reason why new fish owners find their fish floating dead on the water. This is the reason why you should test out your new aquarium with one or two expendable fish, before you bring in the more exotic and expensive kind. This is also the reason why not all the water in the fish tank must be drained during cleaning: you still need a culture of Nitrosomonas and Nitrobacter bacteria to do their job of biologically filtering your tank.