If you are one of those people who have your fish dying on you whenever you set up a new tank or after you have done your tank & filter cleaning, you really need to read this. This is about the Nitrogen Cycle and understanding it will lessen your heartaches and frustrations with keeping your goldfish alive.
Nitrogen Cycle is a very important biological process that needs to happen in order for the environment to be safe for your goldfish to live in. It is a nitrification process by colonies of good bacteria that breaks down toxic chemical compounds to non-toxic.
Nitrogen Cycle Diagram
So how does Nitrogen Cycle work?
Well say we are already keeping goldfish in our tank. We feed them, and they eat happily. After eating, they’ll pee and poop. These fish wastes will produce the first chemical compound, Ammonia in the water. Excess fish food, rotting plants, dead occupants in the tank will decay and produce Ammonia as well. Ammonia is very toxic to fish!
That is when our first hero comes in. The Nitrosomonas bacteria feed on Ammonia and break it down to another chemical compound called Nitrite. Nitrite is also very toxic to fish!
That is when our second hero comes in. The Nitrobacter bacteria breaks Nitrite to another chemical compound called Nitrate, and this is a non-toxic chemical. However high concentration of Nitrate is harmful to fish, so it is recommended to keep it below 50ppm. Nitrate can be removed from the tank via water changes (yes, very required in fish keeping) and it’s also consumed by aquatic plants that you have in the tank.
At the point when we see the emergence of Nitrate and the cessation of Ammonia & Nitrite, we can say that the Nitrogen Cycle is complete or that the tank is fully cycled. This means that the environment is now safe for your goldfish.
But there’s a problem…
In a new tank set up, our bacteria heroes are not big enough to carry out the job. They will need Ammonia (this being their food) to start establishing their colonies and this will take some time (around 2 weeks – 2 months). These bacteria mainly build their colonies in your tank’s substrate and filter media.
So if you already have a fish in the new tank before all these bacteria colonies are in place, that poor fella will need to survive the toxicity of Ammonia & Nitrite as they build up, and with a high likelihood it’s a bye-bye.
This situation also applies if you wiped out the bacteria colonies of your established tank by changing 100% of the water and cleaning the substrate/filter with tap water. These actions basically remove a big portion, if not all of those valuable bacteria colonies and your tank will need to go through the whole Nitrogen Cycle again.
More to come…
As you see, knowing a little bit of chemistry and a little bit of biology do help in understanding what we need to do to keep our goldfish alive. I have only touched on what Nitrogen Cycle is. Check out this post on how to cycle your fish tank.