Cycling the tank essentially refers to growing a colony of 2 sets of bacteria in your tank such that they can break down all Ammonia and Nitrites in the tank. These bacteria are part of the Nitrogen cycle and they take the process up to the last point of the Nitrogen cycle, that is they convert all waste to relatively less toxic Nitrates.

There are 2 ways to cycle a tank:

  • Fishless cycle
  • Fish-in Cycle

Fishless Cycle: By using Ammonia


Instead of using fish food for ammonia production, you can introduce pure ammonia to the tank.

After the tank has been set up, add five drops of ammonia per ten gallons into the water on a daily basis.

Ammonia will rise to five ppm and higher. As soon as nitrites are measurable, reduce the ammonia input to three drops per day. Nitrites will rise to similar levels. Keep adding two to three drops until the measurements of ammonia and nitrites come out with zero ppm. The tank has then completely cycled.

Seeding the tank can significantly enhance this process. It is possible for a cycle to complete in seven days with seeding; otherwise this method takes two to three weeks.

The bacteria colonies produced using this method are large enough to handle a well-stocked aquarium.

Some aspects to consider

• The tank has to be well oxygenated because the bacteria require oxygen.

• The ammonia used should be free of any perfumes and additives.

• Do not treat the water with conditioners that remove ammonia.

Water changes are only necessary if the ammonia and nitrite levels are far off level, which should only occur if more than five drops are used per ten gallons of water. After the cycle has been completed, use activated carbon to remove any possible perfumes or additives that might have been in the ammonia.
After stocking your tank with fish, general maintenance of the aquarium is all that is required. The bacteria will adjust to the fish load, and if you plan to add new fish, the bacteria will have to adjust again.
Remember to feed your tank with ammonia until you introduce fish. The waste generated by your fish will then provide the tank with all that is needed to balance the environment.
With the ammonia drop method, all aquarium types can be cycled in a very short period of time.
Professionals use this method to keep live sand and rock alive to sell in their stores.
We recommend you read about the nitrogen cycle so you have an understanding about what happens during this cycling period. You will also need ammonia, nitrite, and nitrate test kits to perform your daily testing of the water.

Fishless Cycle: Using Fish Food


Another form of cycling the aquarium is without fish. Set up the tank with all the equipment needed: filtration, heater, light, protein skimmer for marine and reef tanks, etc. Start it up, setting the heater to a temperature around 80° F, then simply feed the tank with fish food. The decaying food will release ammonia, and the tank will start the cycling process. To speed up this process, the tank can be seeded with supplies from established tanks, such as gravel, filter cartridges, filter media of any kind, biowheels, drift wood, and rocks.

Bacteria colonize all of the above, so seeding introduces existing bacteria colonies to a new tank. The decaying food will provide ammonia for these colonies to settle and expand in the new tank.


This fishless cycling method requires a similar amount of time as classical cycling. Also, the ammonia produced might be insufficient to create enough bacteria colonies to hold the fish when they are introduced. This will trigger another growth of bacteria with the spikes in ammonia and nitrites.

These renewed spikes, however, will be much shorter and less intense compared to the initial ones experienced during the primary cycle. Consequences for the fish are minimal, making this method more fish-friendly.

Both forms of cycling have one thing in common – Ammonia. A tank has cycled if ammonia and nitrites are back at zero ppm. At this time, you can stock the tank with fish. If no fish are introduced, the bacteria will need to be fed by continuing with the addition of fish food or pure ammonia .


Fish-in Cycle

So, you just bought your new fish and are only just now learning about this cycling thing… Or, maybe you are following the terrible advice of the pet store employee who said you only need to run your filter for 24 hours before adding your fish.

Maybe it’s even worse. You killed all the good bacteria in your tank and have to cycle your aquarium all over again.Don’t worry! These scenarios are much more common than you think.

If you can’t return your fish, then you have only one option:

You have to cycle your aquarium the old-fashioned way – with fish in the tank.

If you haven’t bought your fish just yet, it is recommended to use the fishless cycle, which is an easier, faster and safer way to cycle your aquarium.

With fish in your tank, here’s what you need to do. First of all, be prepared for a 4-6 week exercise regime around your fish! Read on for next steps.

  1. Test the water for Ammonia. Seriously. Get an Ammonia and Nitrite test kit. The more sensitive your fish, the more you need to be precise on when you really need that water change. You will need to test water every day.
  2. Once Ammonia reaches 0.4 ppm, change 50% of the water such that Ammonia gets back below 0.25 ppm. Prolonged exposure to 0.5 ppm Ammonia can get your fish quite sick, so keep your vigilence up during this time. In a few days, you will get a sense of how frequently your tank needs a change of water. Still keep testing as frequently as you can.
  3. Do remember that you need the Ammonia concentration at an average of 0.25 ppm, else the beneficial bacteria will take forever to form their colonies.
  4. Over a few weeks, after an ammonia build up, the nitrites will start showing up in the tests. Water change is really your only saviour.

There could be a few other saviours though, that can shorten your water changing schedule enormously.

Find a friend who has an estalished aquarium already, and borrow some aquarium decorations/ stones/ part of a filter media or any object from the aquarium. Your cycling time will reduce by 2/3rd or more, as you are essentially helping bacteria colonies to take hold faster. you may look a little silly to your friend, but then, what are friends for!!

Introducing plants in the equation can help enormously. Plants take up ammonia directly from the water and don’t let it build up. In fact, planted tanks rarely face a cycling problem. Hence if there is any possibility. get a few plants even on temporary basis, go for it.