Cycling an aquarium is the process of establishing a population of ‘good bacteria’ in an aquarium. ‘Good bacteria’ convert toxic compounds, such as ammonia and nitrite into harmless substances such as nitrate. Without ‘good bacteria’ the fish in your aquarium will die.
Everything organic in an aquarium (wood, decaying plant matter, fish, snails, shrimp etc.) is a source of ammonia. Ammonia is highly toxic to aquatic life and even a tiny amount can kill your fish.
So what is good bacteria? Good bacteria are present everywhere, just not in sufficient numbers to support life. The goal of a filter is to create as much space for the bacteria to live as possible. ‘Good bacteria’ convert ammonia into nitrite and then into nitrate. Nitrate can then be used by plants as a food source. If nitrates reach high enough levels it can become detrimental to fish health. This is the reason why we do water changes; to remove nitrates.
The following is a list of methods used to cycle an aquarium from WORST METHOD to BEST METHOD;
Using a raw prawn to cycle an aquarium is an old, yet inefficient, method of cycling an aquarium. It involves dropping a raw prawn into a newly established aquarium in order to provide a source of organic matter and thus, ammonia for the ‘good bacteria’ to feed on. As the prawn breaks down, it releases ammonia, kick-starting the cycling process. Although a viable method, leaving a prawn to rot can make a mess of your aquarium.
Insignificant Fish Cycle
The insignificant fish cycle uses small fish as a source of ammonia, a by-product of fish waste, to cycle the aquarium. This is by far the cruellest method of cycling an aquarium, as the fish adding are exposed to elevated ammonia levels, often resulting in ammonia burn and a shortened lifespan. You should NEVER use this method.
The addition of detritus or mulm (the gooey stuff you find in the bottom of your filter) is one method used by hobbyists to cycle an aquarium. It involves taking detritus/mulm from a pre-existing aquarium or filter and placing it in a new aquarium or filter. Personally, I would place it in the filter, as placing it in the aquarium will just result in a dirty tank. While this method works, it isn’t perfect.
This method is by far the simplest and most used method to cycle an aquarium. It involves setting up the aquarium and waiting 2-6 weeks for the aquarium to cycle. During that time period the hobbyist should test ammonia, nitrite and nitrate levels daily. The hobbyist should observe a spike in ammonia levels, followed by a spike in nitrite levels. Once these before mentioned levels reach zero, nitrate should be the only readable level. Once this series of events occurs, the aquarium has been cycled.
Direct Ammonia Addition
Many of the above methods add ammonia indirectly; the insignificant fish cycle, the raw prawn, the detritus/mulm etc. However, it is possible to add ammonia directly. Ammonia is used as a cleaning product. Therefore, you can purchase pure ammonia and add small amounts to a new aquarium in order to establish the bacteria population.
Bacteria in a Bottle
There are several companies that sell products claiming to bypass the cycling process. These products generally claim to contain live ‘good bacteria’ which can be added directly to an aquarium. While I have used these products and continue to do so, I never use them as stand-alone solutions. While these products may aid in kick-starting the cycling process, they should never be relied on entirely. Instead, I use them in combination with the next method.
This is by far the best method of cycling an aquarium, as you can add fish the same day that you set up the aquarium. However, if this is your first aquarium, this will not work. It involves taking media (sponges, bio-balls, ceramic rings) from an established filter and placing it in a new filter. The ‘old’ media will have a pre-established population of ‘good bacteria’ on it, so there is no need for cycling!