This is the second article in this series. To read the first click here.

What is an aquarium cycle?

The aquarium cycle, or the nitrogen cycle, is the process of using different bacteria to convert ammonia (toxic) to nitrite (toxic) to nitrate (not so toxic). This process is vital for your aquarium to be successful. As your fish live, they are going to produce ammonia through their poop and leftover food. As this waste decomposes in your tank releasing ammonia which is highly toxic to your living organismims in the tank. Having excess of ammonia in your tank can cause ammonia burns on your fishs’ gills, and death in invertabrates. Cultivating a bacterial colony to break down ammonia will happen naturally with the presence of ammonia in your tank, there are ways we can help it along, which I’ll discuss later.

Once the ammonia is broken down into nitrite, a second bacteria will break it down into nitrate, which is something we can use. Nitrate is fertilizer for plants, it’s in miracle grow, and manure. While you’re cycling your tank, when you see your plants suddenly shoot out new leaves and you have algae blooming, you’re cycle is in full swing. But how do we get to this magical equalibrium?

Cycling the tank

Before adding any animals to the tank (aside from the pond snails that will inevitably hitchhike on your live plants) you’ll need to get your tank running. For more information on setting up your tank, read the previous article in this series here. You’ll need to have your aquascape set up and your plants in before you start cycling. Many bio-media boxes will come with some bottled bacteria, go ahead and use it as directed, it will jump-start your cycle a bit. Throw in something that will rot, I’ve used pieces of meat, fish food, vegetables; really it doesn’t matter, so long as it rots. I replace my rotting item every day, or add more if it’s flake food of some kind.

Do this and start doing your weekly water changes. Do a water test every few days, and just before and just after you do a water change. Keep notes so you can see how your cycle is coming along. What you should see is three curves spiking and falling down in succession as the bacteria consume and produce down the line. If you get a big algal bloom, it’s no big deal, your bacteria and plants are much more efficient at consuming ammonia and nitrate than the algae is, it’ll die off on it’s own (if not, that’s another topic all together).

Once you reach 0 ammonia, 0 nitrite, and really low nitrate, keep up your practice for another week just to make sure and then add your fish!

Fish-in Cycle

“But Tommy,” I hear one of you say “I didn’t know about the nitrogen cycle and the fish was so cute at the pet store and they didn’t ask me any questions like that and so now I’m home and I have this fish and the water is aweful and the fish is acting all sick, what do I do?!?!?!” First, don’t buy fish at the big box pet stores, they can’t actually give you good advice like a local fish store can, and you’ll get higher quality and broader variety of fish at your LFS. But to answer your question, there is a solution, but it’s going to suck.

The fish-in cycle should never be the first option. In reality, if you can temporarily re-home the fish into another tank while you get the cycle going you should. But in the inevitable situation where you have to do a fish-in cycle, here’s how you do it. You’re going to need some supplies:

• Bottled Bacteria
• A filter with tons of surface area like a sponge filter or ceramic bio-media
• Lots of plants
  • borrow some if you have to, but the more the better, even if you don’t want to have that many in the end
• Lots of water changes

As you feed your fish like normal, you’re going to need to do daily water changes, of about 50 per cent. Apply the bacteria as suggested on the bottle, for ceramic bio-media, it’s best to put it directly on the media as that’s where they’ll live anyway. Do daily water tests, and keep the filter on it’s highest flow rating. Buffetting your betta around for a couple weeks is better than it dying of ammonia poisoning. Within a week you should see your ammonia coming down. Hopefully you’ll have learned a lesson and won’t do this again, unless you absolutely have to.

Keeping the cycle alive

So the cycle should be fairly self-sustaining, so long as you keep feeding it the bacterial colonies will stay living and growing. You’ll also need to keep your filtration going. If your filter ever stops for too long, the bacteria will start to die. This is why power outages are so bad for aquarists. If you notice your ammonia spiking and haven’t changed anything then you may be having a problem. Part of your water change system should include cleaning your filtration. Squeeze out your sponges and rub your bags of bio-media in your hands in the old tank water and reinstall. This will get any build-up out of there and get rid of the old or weak bacteria. You don’t want old and weak bacteria. You want your filters to be full of ubermench bacteria.