How to Cycle a Tank Without Fish? (Step-by-Step Process)
Cycling a tank without fish might seem like an unnecessary step to take, but there are actually several benefits to cycling your aquarium this way. Most importantly, it allows you to start keeping fish as soon as possible—often within two weeks of starting the process—and it helps prevent ammonia spikes that could kill your fish before you even get them home.
The first time you go through the process, follow these instructions carefully and give yourself plenty of time. It can take up to three months to complete, so be patient and make sure you do everything properly the first time!

How to Cycle a Tank Without Fish?
Set Up Your Aquarium
To start your fishless cycle, you will need to get an empty tank and fill it with fresh water. You will also need some rock or gravel since this will act as a filter. Place the filter and aquarium decorations of your choice on the bottom of the tank, leaving room for the plants you plan on adding later.

When filling the tank, make sure not to put too much stress on the glass so that it doesn’t break when you add any additional weight from rocks or other decorations. Fill up about 3/4 of the way full before letting any air out of the hose.
Live Bacteria
In order to start a fishless cycle, you need to purchase live bacteria, which are sold in liquid form and are found in most pet stores. Once purchased, it’s very important that you follow the instructions exactly as they appear on the package.

You’ll pour half of the liquid into your aquarium or filter and turn off all power for 24 hours (meaning no lights or filtration) so that the bacteria can develop into nitrifying microbes. It’s also important to not disturb the water during this time by using any nets or other tools. After 24 hours have passed, add the other half of the liquid and turn your filters back on; then wait another 3-5 days before adding any new fish. Some people choose to do a 25% water change after 5 days just to be safe.
The key here is patience because when starting out with an empty tank or tank without any fish inside of it, you don’t want to shock the system too quickly. When starting out with an empty tank and cycling it without fish, do everything right and be patient!
Water Changes
First, calculate the amount of new water needed. New water should be double the old water volume. Next, siphon out half of the water and add new tank water. Repeat this process for two days until all the old water is replaced with new and the nitrite levels start to drop. At that point do another 50% water change to remove the extra nutrients and get your aquarium ready for fish!

Siphon Out Half: Begin by siphoning out half of the water from your aquarium. Then take the fish you want to keep and fill up their space in your aquarium with fresh dechlorinated tap water (tap-water + de-chlorinator). Add about 20 – 30 minutes’ worth of air stones or other devices that will help aerate the surface.
Wait until Next Week/Month
When it comes to starting a new aquarium, there are many factors that should be considered, such as the type of fish you want, the type of tank you want, and how much time you can spend caring for your tank. When it comes to cycling an aquarium without fish, this is also necessary because if not done properly, it can have disastrous consequences. Luckily, there are many things that people can do while their tank cycles naturally that make getting started a lot easier when they add fish later on.
For starters, lots of plastic plants should be used in the tank so that nitrates and ammonia levels aren’t too high before the cycle starts. These plants will help remove some of these harmful substances from the water. An air pump with a good filter system would also be beneficial to keep oxygen levels at optimal levels during the process. Finally, one more thing that can help is putting dry food pellets or flakes into the tank. These will decay and create carbon dioxide which helps promote the growth of healthy bacteria colonies within the tank’s filter media.
The Bottom Line on How to Cycle a Tank Without Fish?
Cycling a tank without fish is an essential step in creating a healthy aquatic environment. It involves establishing a colony of beneficial bacteria that convert toxic ammonia and nitrite into less harmful nitrate. This can be achieved using methods such as adding pure ammonia, fish food, or established filter media. It is important to monitor water parameters and introduce fish gradually once the cycle is complete. By following these steps, any aquarist can successfully cycle their tank without fish and provide a safe and comfortable home for their aquatic pets.