The Nitrogen Cycle

Every fish produces waste which gets broken down into ammonia molecules. Ammonia is extremely toxic to fish and will kill your fish fast if it is not removed from the water. No one has time to do water changes multiple times a day which is why cycling is so important. That is what I will be talking about in this post.

When you cycle a tank, you grow beneficial bacteria that lives mainly in the filter and filter media but also can live on the surfaces of your tank. Fish naturally emit ammonia which is highly toxic to them. The beneficial bacteria breaks those ammonia molecules down into nitrite molecules. Nitrites are still toxic to fish so it has to be broken down into nitrate molecules which are removed from the tank through water changes which I will cover in my next post.

So you’re probably wondering, how do I start to grow beneficial bacteria in my tank? Well that's the trickiest part. There are many different methods of doing this but I am going to share three of the easiest methods with you. With all of these methods, I do recommend starting by adding concentrated beneficial bacteria to the tank. This will jumpstart the cycling process and will cut down the amount of time it will take to cycle the tank. There is no definite amount of time that it takes to cycle a tank but I will share with you how to tell when your tank has been cycled at the end.

With any method you choose, it is necessary to do routine water changes. It is recommended to change 10-25% of the water every 2-3 days. Removing more of the water or changing the water more frequently can remove too much of the ammonia or nitrites that need to be present in order to grow the beneficial bacteria. If having fish in the tank while you are cycling, not changing enough of the water or not frequently enough, can quickly kill your fish.

Pre-Established Media

The easiest method to do this is to find pre-established filter media from someone else's tank that already contains the beneficial bacteria. I know that is easier said than done but that is the quickest method to cycle a tank. Sometimes, local fish stores will give you established media from their tanks but not always. Using pre-established media from a tank that has been cycled will have tons of that beneficial bacteria that you are looking for. I still recommend adding some concentrated beneficial bacteria, however, using pre-cycled media will cut out a majority of the work. Even so, the tank is not automatically cycled. After putting the established media in the filter, put fish food in the tank once a day to continue the growth of the beneficial. Continue this process until the tank has cycled completely.

Fishless Food Cycle

The second method is something I am going to call the fishless food cycle because it is just that. For a fishless cycle, you will need to introduce some sort of waste to the tank to simulate the presence of fish waste that has to be broken down. Using fish food is the most accessible way to do that. You will then add fish food every day (about as much as you would use to actually feed a fish). When the food begins to decay, beneficial bacteria will grow over time to be able to break down the waste. This method is very similar to the first method, however, this will take longer since you will be starting from scratch. Continue this process until the tank has cycled completely.

Fish In Cycling

Another method of cycling is to cycle the tank with a fish in the tank. It is important that if you are going to choose this method to choose a hardy fish that will be able to withstand higher levels of toxins in the water. This process is similar to the food cycling method but it will take slightly less time because you are introducing fish food as well as waste to the tank. While this method is effective, you do run the risk of having your fish die from the toxicity of the water. While it is important to do routine water changes for all of these methods, it is especially important with this one. Continue closely monitoring until the tank has cycled completely.

How To Know When Your Tank Has Finished Cycling

https://www.youtube.com/watch?v=ziXA0d16SfU

There is no set amount of time that this will take. You will know when your tank is done cycling by testing ammonia, nitrite, and nitrate levels. At first, you will notice an ammonia spike. This is expected because there will not be enough beneficial bacteria to fully break down the waste yet. When the bacteria begins to grow more, there will be a nitrite spike. Finally, there will be more nitrate in the water than anything else. Nitrates can not be broken down further so you will need to remove the nitrates through water changes as I mentioned before. Your tank has been cycled when ammonia and nitrite levels should stay at 0 ppm (parts per million). Nitrate levels should always stay between 0 ppm and 20 ppm even after the tank has cycled. Remember, beneficial bacteria is in charge of breaking down most of the ammonia and nitrites in the water, but nitrates have to be removed through water changes so if this number is high, doing a 25% water change should bring that number down.

After your tank has been cycled, you may SLOWLY add more fish to the tank as adding too many fish at a time or add them too quickly may be too much waste for the beneficial bacteria to handle and can cause spikes in ammonia and nitrites again. Continue to test the ammonia and nitrate levels in the tank after adding fish to ensure that you have a happy and healthy tank. Come back next week to learn about fish tank filters!