Filter media

Filter media

Before I added the filter to the aquarium, I removed the activated carbon and replaced it with some porous ceramic media.

I used Substrat Pro by Eheim as the space available was quite small at approximately 6 by 3 by 3 cm and Substrat packs more densely than porous ceramic “noodles” would. I do use a number of different types of ceramic media in my larger filters and can not say that one is any better than the other. There is one point to watch out for when buying ceramic media and that is that some media is not porous: this type of ceramic media is actually intended for spreading the flow of water in external filters before it reaches the porous bio-media, not as purely biological filtration.

The carbon I have removed is now put aside, into a dark, cool storage space, until I will need it to remove the remainders of medication which was used in the aquarium. Even though I do not expect to have problems with the fish, I still keep medication for occasions when a couple of fish may have a pecking order dispute or one may scratch itself on a piece of decor. These are rare occurrences, but impossible to prevent.

There is little sense in using chemical media such as carbon or zeolite on a regular basis because these will mask problems in aquaria and can affect the effectiveness of the filter. I even go so far as to not use any chemical media except carbon, and that only on very rare occasions and only because manufacturers seem to insist on including it with every new filter that I buy. I believe that carbon will be used up in anywhere from few hours up to a few days after being added, and there is consensus between many fishkeepers that at most it would last one week. When it is used, carbon is most effective if the water is filtered through it at a slow rate, which is relatively unusual for an aquarium filter as most fishkeepers aim to have the highest flow rate filter possible.

My preferred filter configuration for most aquaria is rough sponge pre-filter, leading to bio-media and finally passing through a filter wool polishing filter. In this setup, the rough sponge should filter out large pieces of solid waste, the bio-media will deal with ammonia and nitrite, and the filter wool (which is also known as filter floss) will “polish” the water, removing any remaining solid waste. The Powerbio is a two compartment filter: the media housing has a large, rough sponge which is accessible through the bottom and a separate, plastic compartment which is accessible through the top of the media housing. I may add a layer of filter wool later on, but for now, I have settled on the rough sponge with the bio-media.

The filter

Filters are essential to modern fish keeping: they are home to bacteria which make the water safe for the fish.

The nitrogen cycle in an aquarium commences at the point where fish and dead plant matter produce ammonia. Some of the ammonia is then used up by plants, but the majority is converted, by bacteria which live in the filter, into nitrite. Nitrite is then converted by filter bacteria into nitrate. Some nitrate is used up by plants and the rest is removed during water changes.

The general format of a filter is some sort of pump which causes water to move through some media. This is usually in the form of an internal filter, an external filter, an air pump powered sponge filter, an undergravel filter, a sump, a trickle filter, a hang-on-the-back filter, and so on. For this aquarium, I will be using an internal filter, potentially moving onto an external later on.

There are three types of media usually used in filter:

Mechanical media:
This media includes various sponges, wool and floss, it physically removes dirt from the aquarium by not letting it pass through the filter.
Chemical media:
The primary function of this media is to adsorb undesirable certain molecules out of the water: for example, activated carbon can be used to remove the remainder of medication after a completed treatment. Some “chemical media” works on the basis of ion exchange. It should usually not be used on an every day basis.
Biological media:
Bio-media is the best media for the bacteria to live on because it is usually very porous, so has a high surface area. It is usually made out of some sort of ceramic material. In an undergravel filter, the bio-media is the gravel and in a sponge filter, it is the sponge.

The bacteria are not particularly picky, so will actually live on any surface they can, regardless of the type of media used.

The first step for setting up the aquarium will be cultivating these filter bacteria. They are present in tap water in very small numbers, so I will be feeding them ammonia to encourage the colony to grow. Once the colony is large enough to support fish life, I will be replacing the ammonia with fish (who naturally produce ammonia).


The filter which came with the kit is a Powerbio 700 by Classica (which is the Arcadia brand for non-lighting equipment). It consists of a standard filter power head with a screw-on spray bar attachment, on top of a filter media housing which contains a cage for loose media (containing carbon) and a rough black sponge (not carbon). The carbon has already been taken out and I will be replacing it with some form of bio-media. I will keep the carbon in case I ever need to remove medication after treatments.