Perhaps the most single important step of owning a fish tank is also among the most misunderstood parts of owning one. Unless you have been doing your homework and researching fish tanks you probably have not heard of the Nitrogen cycle. Tank cycling is a very important step in establishing your new tank and if not done properly can cause failure from the beginning. In fact, many new fish owners fail in their first month of owning a tank.
Before we start we need to understand what the Nitrogen cycle is. Fish create waste, these waste products are broken down into Ammonia by beneficial bacteria. Beneficial bacteria converts harmful wastes into something less harmful, which is called Nitrite. Nitrite is finally broken down into Nitrate, which is less toxin than either Ammonia and Nitrate. Typically it takes from anywhere from three to six weeks for there to be enough beneficial bacteria to effectively provide enough biological filtration.
The Nitrogen cycle is necessary to keep the water free of waste that cannot be filtered no other way, but while the Nitrogen is going through the process of cycling to establish enough beneficial bacteria to provide proper biological filtration, the fish are exposed to high levels of Ammonia and Nitrite, which can harm them and even result in death. Even if you do not see the effects right away it takes a toll on them and often leads to a shorten life span.
To avoid this you can perform fishless cycling, this is very simple. All you will need is Ammonia. This can be found at most department stores, just make sure it's pure Ammonia and not Ammonia that has any additives because it can harm the fish. You will need an eye dropper to drop Ammonia in the tank and test kit to test for Ammonia, pH, Nitrate and Nitrite. You want the tank to be well oxygenated because the bacteria requires oxygen to grow. The tank should also be fully setup with heater, filter and other things you'll have in the tank.
Add four to five drops of pure Ammonia per 10 gallons of water to the Nitrites becomes measurable, at this point you want to cut back on how much Ammonia you add to two to three drops per day. If at any point the Ammonia and Nitrite levels are off the chart you should make a water changes to Ammonia and Nitrite levels down. Usually a 15 to 25 percent water change will be the amount you need to change, but this does vary from case to case.
When Nitrite and Ammonia are both at zero, the pH is stable and Nitrate is measurable, the tank is considered cycled. A water change of 25% and up to 50% is recommend at this point. After that you should be able to start stocking your tank with fish. The whole process usually takes 2 to 4 weeks depending on temperature and filtration. Remember,guppy, if you don't add fish right away you need to continue to add Ammonia until you introduce fish.
If you rather you can also simply add fish food to the tank. As fish food decays and rots it will release Ammonia. This will start the process of the Nitrogen cycle. Just add a little food each day to keep feeding it. Although, this may be a bit more difficult because you have to put a certain amount of food to get enough decaying food to produce enough Ammonia and this takes a little practice to get the right amount.
There is also the old fashion way of doing this. Adding two to three hardy fish to start the process. These fish must be very hardy because they will need to be tough enough to withstand the high levels of Ammonia and Nitrites that they will face. These fish may become sick and die as they are exposed to such high levels of Ammonia and Nitrite. A few fish that are known as good starter fish and are hardy are Guppies and platies.
What to expect
During the first week to two weeks you will see a steady rise in Ammonia and will reach lethal levels. During this time the beneficial bacteria will start to grow to the point where it can convert Ammonia. During this time period to reduce stress on fish (If you added fish to start the cycle) you will want to perform 15-25% water changes to reduce the stress on fish. This will help keep Ammonia levels down.
After that you will see a drop in Ammonia levels and a spike in Nitrites. Over the next week or two the bacteria needed to convert Nitrites to the less harmful Nitrates will begin and build enough to see it drop to zero. During this period you will need to perform 15-20% water changes to reduce the stress on fish. This will help keep Nitrite levels down.
At this point you should begin to get Nitrate readings. There is only one way to remove it and that is through water changes. You will need to do weekly water changes of 10 to 15 percent. Fish can tolerate levels of around 40-50ppm, but it is best to not let it reach levels near that. If it reaches levels over 20 ppm it is best to perform a 20 to 25 percent water change.
While the process can seem daunting and a lot of work to those unfamiliar with cycling a tank it really is not that hard. Once you learn how to do it and understand the process it is easy as riding a bicycle.