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.