How to Quickly Cycle a Fish Tank


Aug 3, 2020
Reaction score
I am setting up a new 55 gallon aquarium and I'd like to know if there are any tips or tricks I can use to get a cycle going faster than the weeks I would normally have to wait by letting it happen on its own. Does anyone have any advice for instantly, or at least quickly, cycling a tank?


Aug 8, 2020
Reaction score
There are three/four methods for cycling a fish tank that I can think of. I'll explain what they are down below. But first, let me explain the cycle itself.

The Nitrogen Cycle​

The cycle goes like this:

1. You add fish and food to your tank. The food is nitrogen.
2. The fish consume the food and excrete it as ammonia.
3. A bacteria grows (Nitrosomonas) that eats the ammonia and converts it to nitrite.
4. Another bacteria is formed (Nitrobacter) to eat the nitrate and turn it to nitrate.
5. Live plants absorb the nitrate and ammonia and use it as fertilizer for growth.

Nitrate is relatively harmless, but you do want to be sure to keep it under 40ppm by doing water changes. Live plants do help with keeping the nitrate in check by consuming it. You will need to trim your plants periodically, however, to remove the nitrate from the system.

So that's your desired cycle. Unfortunately, that natural cycle takes a few weeks to establish. It's all that beneficial bacteria growth that takes time.

Naturally Cycling a Fish Tank​

Onto your options for creating a cycle for your aquarium.

First, you can simply let it happen by itself. Add water to the tank and set up your aquascape. Wait a few days for the water to get to temperature and for things to settle down. Then, add a (hearty) fish or two. Feed as you normally would and then wait a few weeks while feeding and caring for the very few fish you added. By adding only a few fish, you'll be less likely to have created an ammonia spike than if you had added many fish. If you add too many fish to the tank without any of that beneficial bacteria growing, there will be nothing to eat the ammonia the fish produce. Ammonia kills fish. So you definitely want to add your fish very slowly.

Adding Ammonia Directly (Without Fish)​

I've heard that some people out there within the aquarium community have added small amounts of ammonia directly to their tanks after setting them up, but before adding fish. Allegedly, this can jump-start the nitrogen cycle. I'm not sure of the amounts and I'm not sure if this works, but it seems to be a think. If you think about it, it should work. The introduction of ammonia should prompt the growth of the bacteria. Once the cycle is complete, you can add your fish. If this method interests you, let me know down below and we can do some investigating to see how it can be done successfully.

Use a Store-Bought Solution​

There are many over-the-counter cycle jump-start products you can buy. One I know of is called Fluval Biological Enhancer, otherwise known as "Cycle" in some places. Another product is called FritzZyme 7, which I've heard good things about. Do your homework before buying any of these because from what people say, many of these types of products don't work when it comes to the nitrification process. In theory though, by adding a cycling chemical to your tank, you should get the cycle going very quickly.

Pulling From an Established Tank​

If you are big into the fish keeping hobby and if you have more than one tank, you're in luck. This last option is definitely the best and it's the one that pretty much everyone who already has an established tank uses. Basically, because the sought after beneficial bacteria lives on surfaces, such as glass, stone, wood, gravel (substrate), plants, and filter media, it's very easy to simply borrow some items from the established tank to add to the new tank. A common item to take from the old tank and add to the new tank is filter media. When I personally need to start a nitrogen cycle in a new tank, I take the entire filter from an established tank and just use it in the new tank. That's really all it takes. The results are instant. Another option is to take the old media from the established filter and tuck it behind a foam filter, if that's what you're using. If you've got extra plants, put those in the new tank. Extra gravel or rocks? Same thing. Basically, anything that's got the bacteria growing on it will help out tremendously. After doing this though, I'd still wait a few days, just to make sure the temperature is okay and to make sure the water is filtering through the entire tank. I like my tanks to sit for a while before adding fish.

No matter which method you use, be sure to always add fish slowly. There's an entire science behind ammonia load and how much bacteria you have in your tank. You don't want to cause a dangerous ammonia spike that may kill some of your fish. In this hobby, slower is better.
How to Quickly Cycle a Fish Tank was posted on 07-01-2021 by KristinaW in the Home Forum forum.

Similar threads

Forum statistics

Latest member