It’s one of the oldest conversations in fishkeeping, but it’s nice to know that as time goes by, the options are improving. Tom Ackrill looks at starting up a biological filter.

TOM ACKRILL

Tom is the founder of the Freshwater Fishkeeping Facebook page and has a fondness for helping newcomers.

THE SUBJECT of setting up, cycling, preparing, and maintaining filters is one that seems to plague fishkeepers right from the get go. Until you’re comfortable with what’s going on in the micro-world inside that little humming box in or under your aquarium, the idea of ‘cycling’ a setup becomes extremely confusing. To try and clear up this common pitfall for newcomers, here’s a few of the most common questions around filters.

Why do I even need a filter?

Fish, like all living creatures, produce waste. In most cases, this is excreted in the form of ammonia (although some species produce urea instead, which then decomposes to ammonia later). That ammonia is toxic to our fish, with some species better able to withstand exposure than others, but nevertheless, it is not something we want sitting around in our tanks. To combat this, we take advantage of some of nature’s most useful microorganisms. Various species of microbes, such as Nitrosomonas bacteria, and possibly some species of archaea, are able to convert that ammonia by consuming parts of it as a food source in the presence of carbon. This then converts to nitrite, which is later converted to nitrate — the last of these compounds being considerably less toxic than the former two. The nitrate component is then either used as nutrient by plants, and/or removed by water changes. This process of cultivating and maintaining this bacterial colony, is what we mean by ‘cycling’. There have been many attempts over time to perfect a ‘filterless setup’. Realistically, the amount of effort to try and do this, and maintain optimum water chemistry and fish health, renders the choice of a filter far superior in most cases.