A nitrogen cycle is the process of converting harmful ammonia gases in the aquarium water into nitrogen which finally escapes into surrounding air. Primary source of ammonia is decaying of solid waste produced after fish digest the food. Nitrogen is practically harmless to aquarium fish and the ultimate goal of every fish keeper is to achieve this stage as soon as possible in their fish tank setup. Tough converting harmful ammonia into nitrogen is very difficult at least you can do is get ammonia converted into nitrates that are less harmful for fish.
As fish are living in a closed environment even after the ammonia levels are down once the tank gets cycled, very quickly they will rise because fish will keep on eating and producing solid waste that get converted into ammonia, nitrites and nitrates again and again.
To tackle this issue you must have a colony of beneficial bacteria present in your tank that will break down toxic gases and make your fish tank a habitable place of fish community. So cycling is a continuous process and must be given the highest importance in fish keeping.
Another way to maintain safe levels of gases is to do water changes regularly which keep the levels under control and fish tank a habitable place.
Factors that produce ammonia in a fish tank.
The primary source of ammonia generation in any fish tank is the solid waste produced by fish. Since a fish tank is a closed environment, the solid waste does not flow anywhere like in natural settings. It gets settled at the bottom of the tank and slowly gets converted into ammonia because of decaying, which is extremely toxic and can cause burns on fish body. If not treated or removed this can kill all your fish one by one. That is why water changes are recommended to keep ammonia and nitrite levels minimum in a fish tank.
However the ultimate and the best way to cycle a fish tank is to add beneficial bacteria in the tank which turns ammonia into nitrites and nitrites into nitrates which are slightly less harmful as compared to ammonia and nitrites.
Some fish are hardy and will get along with slightly higher numbers of ammonia and nitrite levels but is not an option and must be treated. Apart from fish solid waste, some other sources of ammonia could be.
- Dead plants
- Medicines to treat a sick fish
- Uneaten food particles that settle at the bottom of the tank
- Dead fish if any
- An overcrowded fish tank
- A small filter for a big tank
All these reasons look very logical because the to tackle high levels of ammonia you must have big amount of beneficial bacteria in the tank and all these above mentioned reasons keep on adding ammonia in high levels continuously. If the amount of ammonia being produced is too much then to tackle this attack you must have the same or higher strength of army of beneficial bacteria to tackle the attack.
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How long does it take for a fish tank to cycle?
There is no exact number that can be considered but is certainly in weeks. Converting harmful ammonia into harmless nitrogen happen step by step and during this process as a fish keeper you’ll need to test water several times and check gas levels in your fish tank.
How to speed up the process of nitrogen cycle?
You can definitely speed up the process of nitrogen cycle and reduce the required time of this by adding beneficial bacteria in the fish tank. The beneficial bacteria then breaks down the harmful ammonia into nitrites and then into nitrates. Nitrates are still harmful but not as that of ammonia and nitrites. Once you get satisfactory test results as far as nitrates are considered you can start adding fish into your fish tank one by one.
How to add beneficial bacteria in the fish tank?
One of the best ways to add beneficial bacteria into fish tank is to use sponge cartridge of an existing fish tank that has been cycled. Beneficial bacteria are present on surfaces and not in water. If an existing fish tank that has been cycles has sponge filter, decorating items, then you can pick some from these and put it in your fish tank that you are trying to cycle. This will greatly improve water conditions and speed up the cycling process.
Do water changes on a regular basis speed up process of nitrogen cycle?
Water changes will speed up the process of nitrogen cycle but is not recommend because when you change the water that has been process by the beneficial bacteria, all the time that has spent till now will be wasted. Also the new water will have its’ own ammonia and chlorine content to some extent which needs to be treated. So by changing water you are disturbing the cycle instead of improving it.
Once you introduce beneficial bacteria into fish tank all you have to do is let them do their job and wait for ammonia and nitrites level to drop down to zero. The only condition when you’ll need water change is when you already have fish in your fish tank and ammonia levels are too high. You must own a good quality water testing kit to identify the levels of ammonia and nitrites.
How do I know when my fish tank has cycled?
A surefire way to know if your fish tank is ready for occupancy or has been cycled is to test water using a water testing kit and get ammonia and nitrites levels with zero reading. You’ll have some nitrates present in water but these are comparatively harmless to your fish. The nitrogen cycle is complete when even these small percentage of nitrates get converted into “Nitrogen” that gets released into surrounding air.
What happens if you don’t cycle your tank?
Cycling a fish tank is absolutely necessary because health of your fish community depends on it. By cycling a tank you are removing toxic gases like ammonia from water and making it healthy for fish. Its common sense that what will happen if you don’t cycle your fish tank, your fish will die sooner or later. Some fish species will survive for a longer time because they have the power to sustain in slightly rough conditions than others. But if you don’t follow rules of nature then the results are going to be disastrous for fish.
If you don’t cycle your tank then eventually the toxic gases will kill your fish. Adding your fish too early in a new tank before the tank has cycles completely is also a bad idea. If you are new into fish keeping then avoid adding your fish too early in the tank. You must keep testing the water for toxic levels and only think of adding the fish when the cycle is complete.
How long do you let water sit before putting fish in?
If you let water sit without fish in it then it will get cycled by itself but can take days or even week to do this. During these idle days you must keep testing the water for levels of ammonia, nitrites and nitrates so that they are not harmful anymore. It all depends on how fast the beneficial bacteria grow in this tank and once they start growing they break down harmful gases making it a habitual place for fish. How long it takes to cycle the tank also depends on how big your tank is.
You can get beneficial bacteria from a tank that has already been cycled. Normally these bacterial are present on decorating surfaces of a tank or on a filter media. You can get a piece of that from a tank that has already been cycled and introduce it in your fish tank. Normally a lot of dirt also comes in with these older media but that can be easily tackled and it’s not a big problem. Sometimes when you add old filter media it is likely that it will also bring harmful bacteria, snails, pest etc. But these are not as harmful as toxic gases mentioned above.
Another way to add beneficial bacteria is to buy them in bottle. If you plan to buy the bottled bacteria then you must remember that though the bottle says you can add fish immediately, you should never do that because these bottled bacteria just boost the process of cycling the fish tank and before you add the fish you must check the quality of water using a water testing kit for ammonia and nitrite levels.
Can I use water from a cycled tank to speed up cycling process of my new tank?
The short answer is no you can’t because beneficial bacteria are present not in the water of an established tank but it’s on the surfaces like gravel, decorating items, filer media etc. If you add water from a cycled tank it won’t help in any way but if you add any of the parts of the surfaces from an established tank then it will certainly help to speed up the process of cycling.
Do aquatic plants speed up the process of nitrogen cycle?
Yes aquatic plants do help in maintaining a healthy nitrogen cycle. As mentioned earlier beneficial bacteria first convert toxic ammonia into nitrites and then nitrites into nitrates.
Aquatic plants can consume nitrates in a tank and control the levels easily. However having a planted tank is an altogether different topic and out of context of this blogpost.
Having a planted tank can have two dramatic effects in your fish tank health. Firstly your tank looks lovely and beautiful visually because of live plants. It looks natural in all way and visually more soothing and appealing from outside.
Secondly as mentioned above plants can consume almost all of nitrate levels maintaining healthy levels of gases present in the water.
However having a panted tank can have other added issues such as you’ll require extra lighting above the tank for the plants to grow naturally and this means an extra cost of the lighting system and electricity. So before jumping into having a planted tank study carefully all the aspects of setting up a live planted tank to tackle the issue of nitrogen cycle.
If you have live plants then the need to do water changes will also reduce because when you test your water using a water testing kit you’ll find balanced levels of toxic gases the need to change water frequently will be eliminated.
What are ideal levels of Ammonia, Nitrites and Nitrates in a cycled fish tank?
Ammonia – 0 ppm (parts per million). Even smaller amounts of ammonia like 0.25 ppm can cause serious damage to fish gills.
Nitrites – 0 – 0.75 ppm (parts per million) are idea and levels above 0075 ppm are dangerous for fish health.
Nitrates – 40 ppm (parts per million) and above is dangerous for most fish. Ideally for most fish less than 20 ppm will work best.
If after testing water you find that ammonia levels are too high then you can do a 50% water change.
Precautions to look for to maintain healthy levels of gases in a cycled tank
1) One of the most important things to avoid is to add medication in your main fish tank for treating a sick fish. Always have a quarantine tank to treat sick fish. if you find a fish is sick then remove it from main tank and put him in a hospital tank and add medication there.
This is because medication in a fish tank will kill ammonia and nitrites, but it will also kill beneficial bacteria bringing a huge spike in ammonia levels completely disturbing the nitrogen cycle.
2) Avoid overstocking your fish tank just because it look good visually or you have love for certain types of species. More fish means more solid waste and the beneficial bacteria will have more load to convert the higher levels of toxic gases to convert to nitrates. Over stocking fish also means that there will be more uneaten food particles settling at the bottom of the tank causing decay and higher levels of toxic gases.
The beneficial bacteria won’t be able to cope up with these higher levels of toxic gases and the nitrogen cycle will crash eventually causing rise in sick number of fish in the tank.
3) When you maintain your tank many people rinse the biological filer media into sink and wash off the beneficial bacteria into that. This must never be done because sink water has chlorine present in it and when you wash the sponge filer that comes into the tank when you insert t he washed media again in the filter and into the tank.
All the beneficial bacteria that have grown on filer is necessary and is responsible for maintaining the nitrogen cycle and must not be washed off casually. Instead of washing the media in the sink you can wash it in a separate bucket and fit it again with some amount of water in the bucket itself.
4) Don’t overfeed your fish because fish will not eat all the food particles and some will get settled at the bottom of the tank in the gravel bed. This settled uneaten food is difficult to clean and even after much trails some will definitely stay in stuck there no matter how efficiently you clean the bed. These settled food particles start decaying and produce ammonia which as mentioned above is extremely harmful.
What you can do is observe everyday how much food your fish eat and drop only that much quantity to further avoid any decaying of the uneaten particles.
5) Install a biological filter that will keep the water clean and healthy by treating excess mixed toxic gases in the watr. The biological filter will make sure that the nitrate levels that are remained in the water once the nitrogen cycle is complete are kept to safer levels always.