Cycling Your Aquarium

Basic/Background information:
There are two stages that must be considered:

Stage One:
Fish produce ammonia through waste products. In a healthy, established aquarium ammonia is broken down by bacteria to Nitrite. This 'good' bacteria has grown to a number that can break down the amount of ammonia produced, but this takes time. Ammonia is a toxin to fish, and should not exceed very small numbers (if not none) in an aquarium. The problem arises in newly set up aquariums. Clean pebbles and clean water are put in, and no bacteria are present. Often, people put their fish in at this stage too, however this is not a good idea!

The fish bring in some of this 'good' bacteria, but the fish will also produce ammonia. The rate at which the ammonia is produced exceeds the rate the bacteria can multiply and break down the ammonia. In other words, there will be too much ammonia and the fish may be poisoned.

Stage Two:
There are another group of 'good' bacteria that then break down the Nitrite (that the first group of bacteria has produced). This Nitrite is also toxic to fish and cannot remain in the aquarium. The nitrite is converted to nitrate, which is relatively harmless to fish.

When the two bacteria's are working together they form a cycle, known as the nitrogen cycle. When this cycle is operating properly there will be limited amounts of both ammonia and nitrite in the aquarium. This can be achieved through a process known as cycling, which will be detailed below.

So why does this happen in aquariums?
In nature, the amount of water per fish is very large. The wastes produced by the fish are immediately diluted by water to a level that is safe.
Why do my fish get sick then?
Because the two toxins, ammonia and nitrite, are poisoning them. It affects some fish more than others, and most of the time goldfish will not be affected at all by the process of cycling. Some fish however are very sensitive, and death is certain.

This is a diagram illustrating the cycling process. The time will vary depending on the size of the aquarium, and if 'seeds' (detailed below) are used.

What happens if I don't cycle my aquarium?
The few hardy types of fish may not be affacted at all, and will simply live through the less than adequate conditions as the tank cycles itself. However even the tough fish go through large amounts of stress and discompfort, and are not insured against death.

As for symptoms, fish may sit at the bottom of the aquarium, without much movement. They may also go to the surface of the aquarium, gasping for air. The may appear lethargic and off colour. Burning to the skin may occur, if so the skin will appear red and excess mucus may be produced. Their gills may appear brown or lilac in colour. Have a look at ammonia poisoning, and nitrite poisoning for more in depth info.

The Fishless Cycline Method:
There are some people who believe using cheap fish like feeder goldfish are the best way to cycle. I.e. They just buy a couple, chuck them in the toxic tank, and wait for the water to become safe. In the meantime, the poor fish may die or go through horrible stress. And most of the time, the feeder goldfish aren't even kept for the aquarium. The are just used and disposed of.
I don't agree with this method, although it may seem easier to people who only keep expensive tropicals.

Really, all that is needed to kick start the cycling process is ammonia. That's what the fish produce that begins the cycling process, so that's all that really needs to be added. The good bacteria that fish also bring in is everywhere, even in the air! However relying on the bacteria from the air alone might take some time so it is a good idea to 'seed' the aquarium with some bacteria first. Below is a step by step plan to guide you through the fishless cycling method:

Step One: Buy an ammonia testing kit and a nitrite testing kit. These are not too expensive and essential!

Step Two: Set up your aquarium as you like it. Add all your pebbles, rocks, ornaments, plants, filter and purified water.

Step Three: Add the ammonia. This is the tricky part. You want the ammonia level to read about 4ppm when you test it. Between 3 and 5 will do. Gradually add very small amounts of ammonia, testing every 30min or so until the reading is where you want it at.

Step Four: This is time to plant your 'seeds' for the cycling process. If you already have an established aquarium in the house.. or know of one, this is great! Just make sure it is healthy with no signs of disease. Take a handful of gravel and perhaps a cup of water at add it into your new aquarium. Putting aquatic plants in also brings in bacteria with it, so buy some plants and add them too.

Step Five: The cycling process may take a few weeks, depending on your aquarium size. Very small aquariums may only take a week when the 'seeds' have been planted, and about double that if no 'seeds' have been used.

Step Six: Test your aquarium every day for ammonia and nitrites. At first there will be high levels of ammonia and no nitrites. Then, as the ammonia starts to decrease the nitrite levels will increase. After that the ammonia levels will go down to zero, and the nitrite levels will remain high. The nitrite levels will the start to decline as well… you are almost there! Nitrate levels will start to rise and soon there will be no nitrite left! There is no need to buy a nitrate testing kit however. When there is no longer any nitrite, you aquarium is cycled. Congratulations!

Step Seven: Perform a large water change (with purified water), of about 60-70%. Wait another one or two days and you are ready to go.

Step Eight: Do one last test for ammonia and nitrites to make sure everything is still running smoothly. Add your fish and watch them thrive in their healthy aquarium.

Notes:

• It's a good idea to write down your recordings as you take them each day. This way you know where you are at in terms of the cycle. Compare it to the diagram above, and you will be able to estimate the amount of time remaining.
• Throughout the whole cycling process do NOT clean the filter, gravel or anything. Let the bacteria live!
• If you are planning on a large community tank, add fish slowly. Add them over the course of a few weeks or so, or abut one or two every few days. This will give the bacteria a chance to keep up with the growing amount of ammonia the fish are now producing. If you are only planning on a couple of goldfish, you can put them in together.

Ok, so perhaps this information has come a bit late, and you've already added your fish without cycling. Your fish may appear sick, or the water may be cloudy. If the water is cloudy, it means the bacteria are out in full force. In this situation, change about 50% of the water. Then everyday after that change another 30% of the water until the problem calms down. Test the water for ammonia and nitrites, and keep changing water until the levels are at 0. Eventually the bacteria will win and the tank will be cycled, changing the water everyday prevents the ammonia and nitrites getting way too high for the fish.

The same advice goes for those who do not have cloudy water, although it may take a little longer. Just keep testing the water and changing it until all is well again.

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