Every new aquarist is faced with the cycling of an aquarium. However, this important concept is readily misunderstood or overlooked by many new to the hobby.
The nitrogen cycle is referred to in many ways by fish hobbyists: cycling, nitrogen cycle, biological cycle, etc. When you hear these terms, it can be a whole new world, especially if you’re not that keen on science. In actuality, it’s not as difficult a concept to grasp as it first seems. In this article, I will provide the basics on cycling.
Cycling Basics
There is a type of bacteria known as nitrifying bacteria. There is more than one type, actually, but for our purposes we’ll consider them to be one group. This bacteria is present almost everywhere.
The cycling process begins after you set up your aquarium, fill it with water, and provide a source of ammonia for the bacteria to “feed” on. Without the ammonia source, the tank will not cycle. In the diagram given, to the top left, the source of the ammonia is the fish’s waste and excess food given to the fish. The bacteria change the harmful, even deadly, ammonia produced by the fish and food into nitrite. Once transformed to nitrite, another still dangerous chemical, the bacteria change the nitrite into nitrate (note the spelling difference).
Nitrate is much less harmful than both ammonia and nitrite. Nitrate is the final product, if you will, of the cycling chain. Nitrate is harmful, however, in certain quantities. The amount usually considered to be harmful is above 40ppm (ppm: Parts Per Million) on your test kit. This chemical is easily controlled with regular, sufficient water changes.
Water changes are also helpful during the cycling process, depending on how you choose to cycle. Once the process has finished, your test kits should register no ammonia and no nitrite in your aquarium. Nitrate should be within safe parameters, less than 40ppm, and your bacteria colony should now be established and ready to maintain a balance in your aquarium. There are a few ways you can achieve a fully cycled aquarium, which will be listed below.
Cycling with Fish
One of the more common ways to cycle an aquarium in earlier years, and even today, is to add one or two fish. The fish, as shown in the diagram, will provide a source of ammonia from their waste and from excess food in the aquarium and the cycling process will begin. If choosing this method of cycling, you must be careful in how you go about it.
For one, you cannot add too many fish. A couple of fish is usually sufficient, depending on the size of the aquarium. If you add too many fish or overfeed during cycling, you will create much more ammonia than necessary. Any level of ammonia is harmful and is not present in a healthy, cycled aquarium. While cycling, you have to combat the production of ammonia to insure that your fish will survive the process. Small, regular water changes are suggested to protect the fish during cycling. (Remember, water changes help to remove the chemicals, but some level of ammonia must be present to cycle the aquarium.) You will have to continue to monitor the water parameters (ammonia, nitrate, nitrite) closely as well as perform the water changes until the end of cycling to keep your fish from being harmed.
Most fish and pet stores will suggest you cycle with a goldfish. I could not disagree more. Goldfish grow far too large and create emmense amounts of waste. In the end, it's best to choose a fish you will be keeping and can care for.
For the safety and concern of the fish, I do not recommend cycling with fish.
Fishless Cycling
There are a couple of ways to cycle your aquarium without putting lives at danger. Again, you have to provide a source of ammonia for the bacteria to become established. This source can be pure ammonia you can purchase from a store, pharmacist (chemist), or the like. In some areas of the world, pure ammonia is not as easily obtained, and you will have to look to other sources.
Decaying Matter
As gruesome as it sounds, it is effective. If you cannot find pure ammonia and are opposed to using live fish, you can add a dead prawn or shrimp that would normally be used for human consumption. The decaying prawn will provide a source of ammonia for the bacteria, and the cycling process will continue. With this method, since there are no living creatures in the tank, you do not have to do small water changes.
Seeding the Tank
This method proves to be an almost instant cycle. Not only does it add a source of ammonia, but also adds established bacteria to your tank. Here is how it’s done.
Once your tank is set up and filled with water, you can add filter media from an already established aquarium. The media is best obtained from a cycled tank you already have running or from another hobbyist. You can ask a fish or pet store for filter media from one of their tanks, but you are also opening up your aquarium to any disease or parasites that might be carried in the media.
As with any of these methods, it is necessary to have test kits to measure the ammonia, nitrite, and nitrate levels at least. Once your tank is cycled (ammonia=0; nitrite=0; nitrate=less than 40ppm), you're ready to add fish. It is recommended that when adding fish to your newly established aquarium you do it slowly. Don’t misunderstand the concept; fish will still produce ammonia, but if added in the right amount, the bacteria that has become established in your tank should be able to convert the dangerous chemicals without causing harm to your fish.
Resources:
thekrib.com;
freshaquarium.about.com; personal experience and knowledge. Diagram by Leah Curtis.
Recorded as being discovered in 1896, the Longspine Thornyhead, known in the fishery trade as the idiotfish because of its bug-eyed appearance, is now considered to be in danger. In the last ten years alone the population of S. altivelis has dropped an amazing 50 to 60 percent. The decline in population is largely due to the unchecked harvesting of this species by fisheries.
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