How to Cycle a Tank: Version 2.0
Hi! I decided to remake this fairly popular post, as it was made a few years ago, and I’ve learned a lot more about cycling in that time! This is going to be a long, but hopefully informative post, so hear me out! There will also be significantly less swearing in this one as well.
So a “cycle” refers to the nitrogen cycle in aquatic environments. It looks like this:
There are two types of bacteria that colonize during the cycling process. Nitrosomonas and nitrobacter. Nitrosomonas convert the ammonia fish produce into nitrite, and nitrobacter convert the nitrite into nitrate.
While the presence of any of the three can cause oxygen starvation, ammonia and nitrite are the easiest to accumulate to dangerous levels, and have the highest toxicity rate.
Ammonia is produced by the fish and is toxic, to the point of causing damage to major organs if exposed to it for too long. It is either removed from the tank by water changes or through the nitrogen cycle.
Nitrite is also extremely toxic, and its presence can cause a rise in a protein called methemoglobin, which essentially makes the blood unable to carry oxygen. It is either removed from the tank by water changes or through the nitrogen cycle.
Nitrate is the least dastardly of the three stages of the nitrogen cycle. It is only toxic in higher numbers (over 40 ppm). It is only removed from the tank either by water changes, or by plants consuming it (which is why a densely planted tank tends to have better water quality than a tank with fake plants).
So, How Do I Cycle a Tank?
The Things You Will Need Are:
an API Freshwater Master Test kit
a bottle of pure ammonia (can be picked up at the 99c store)
bottled beneficial bacteria
a cute lil notebook and pen
Test your tap water! Ideally, your tap water should read:
If it doesn’t have all zeroes to start out with, that’s okay! If your tap water has ammonia or nitrite when you start cycling, that’s fine! The bacteria you culture should take care of those as you cycle your tank. If your tap water has nitrate, keep that in mind as you cycle, as it might get a little confusing when you test the water. Take notes on your water quality as you go along.
Dose your tank with ammonia!
Add ammonia to your tank until the test reads ~5 ppm. For me, using dollar store ammonia, that ended up being 5ml. Your ammonia might have a different concentration, so add little bits at a time and test. The test doesn’t have to read EXACTLY 5 ppm. A little more or a little less won’t hurt. Just keep in mind that too much more than 5 ppm can overwhelm bacteria that you might be growing and slow down the process, and too much less than 5 ppm can starve the bacteria and slow down the process.
Add beneficial bottled bacteria!
So, there’s a lot of debate on whether or not these things actually work. I personally think they’re worth the $7.00 you may drop on them, because they may just save you weeks of waiting and water testing. I personally used it to cycle my ten gallon, and it sped up the process enough to allow me to cycle the tank in two weeks versus five or six. The only brand I’ve used specifically is Imagitarium (a Petco brand), but, again, using it sped up my cycling process quite a bit. Just don’t bother faffing about with the instructions on the back if you’re using Imagitarium. Dump a bunch in until you feel like you’ve added enough. Just go with your gut on this.
Test a lot. Add more bacteria. Once the cycle gets going, you’re going to be looking at readings like:
Not those exactly, but something probably around that. Keep in mind, your tank is NOT cycled yet.
When your ammonia levels start to decrease, dose the tank back up to 5 ppm. Make sure you’re taking lots of notes on what you did, how much bacteria/ammonia you dosed the tank with, what your readings say for that particular day, etc. Keep in mind, this is a process that may take multiple weeks.
“But Candace, how do I know when my tank is cycled?!”
You’ve waited. You’ve waited a LOT. But there’s really only one way to know if your tank is cycled.
Once you get those readings, you need to do one more thing. Just one more thing.
Dose your tank with ammonia again. Up to maybe 2 or 3 ppm. And wait 12 hours. If your bacteria have successfully converted the ammonia all the way to nitrate in 12 hours, your tank is cycled.
Do a 90% water change, and do some fish shopping.
Use an aquarium heater to get the tank to around 85 degrees Fahrenheit. This is around the ideal temperature for the reproduction of beneficial bacteria. You can lower the temperature to whatever it needs to be before the fish are put in.
Adding plants before the cycling process is finished might skew your readings a little bit as the plants absorb nitrate from the water. If you want to add plants before the tank is finished cycling, make sure you note that and watch for changes in your nitrate tests.
If anyone has any points I’ve got wrong, if they want to add anything, or have any other tips and tricks, they are welcome to reblog with more information!
