The Nitrogen Cycle
The Nitrogen Cycle is the process of converting ammonia (fish waste) into a less toxic form, creating a safe environment for your Goldfish to live in. This is the key to successful fish keeping and is the most important thing you will do. An established Nitrogen cycle is vital in maintaining a healthy aquarium.
How does it work?
Fish produce waste. They don't just poop it out, they also excrete ammonia through their gills. Ammonia is extremely toxic to fish and, if left to build up, it can make fish extremely sick and can be fatal. To create a healthy environment, we need to establish nitrifying bacteria in the filter, which will consume the ammonia and convert it to a less toxic form. This process sounds complex, but once you understand and establish your cycle, you're well on your way to success.
Put quite simply;
AMMONIA ---converted to---> NITRITE ---converted to---> NITRATE ---removed via---> WATER CHANGE
Fish, decaying plants and uneaten food, amongst other things, produce Ammonia. The first of our nitrifying bacteria, Nitrosomonas, establish and consume ammonia. In return, Nitrosomonas produce Nitrites, which are also very toxic and can be lethal in even small quantities. The nitrites are then consumed by Nitrospira, which produce Nitrates. We then manually remove the Nitrates via water changes.
A cycled tank reads 0ppm Ammonia, 0ppm Nitrite and has a reading for Nitrates. We want to keep our nitrates as low as possible. Over 40ppm is considered high. Ideally, we want to keep them below 20ppm, but as close to 0 as possible is ideal. Plants (aquatic and terrestrial) can help to remove Nitrates and some tanks which are heavily planted will have no nitrates (unlikely with Goldfish poop machines!)... This does not remove the need for water changes, there are many other reasons these are performed. 50% weekly water changes are BARE MINIMUM, regardless of your nitrate readings.
Optimal pH for building a colony of nitrifying bacteria is 8.0-8.3 and a temperature of 25-30c. That doesn't mean it's not possible outside these boundaries, but they do aid the process.
Put quite simply;
AMMONIA ---converted to---> NITRITE ---converted to---> NITRATE ---removed via---> WATER CHANGE
Fish, decaying plants and uneaten food, amongst other things, produce Ammonia. The first of our nitrifying bacteria, Nitrosomonas, establish and consume ammonia. In return, Nitrosomonas produce Nitrites, which are also very toxic and can be lethal in even small quantities. The nitrites are then consumed by Nitrospira, which produce Nitrates. We then manually remove the Nitrates via water changes.
A cycled tank reads 0ppm Ammonia, 0ppm Nitrite and has a reading for Nitrates. We want to keep our nitrates as low as possible. Over 40ppm is considered high. Ideally, we want to keep them below 20ppm, but as close to 0 as possible is ideal. Plants (aquatic and terrestrial) can help to remove Nitrates and some tanks which are heavily planted will have no nitrates (unlikely with Goldfish poop machines!)... This does not remove the need for water changes, there are many other reasons these are performed. 50% weekly water changes are BARE MINIMUM, regardless of your nitrate readings.
Optimal pH for building a colony of nitrifying bacteria is 8.0-8.3 and a temperature of 25-30c. That doesn't mean it's not possible outside these boundaries, but they do aid the process.
How do I cycle my tank?
Cycling your tank can take 6-8weeks but once established, will create a safe environment so your fish can thrive in their home. A fishless cycle is the most preferred option as this spares fish any potential stress they may go through during a cycle.
Should you have fish already, managing with close monitoring and daily water changes is the best route, especially with Goldfish as they produce huge amounts of waste. I'm sure many of us have been there, we trust employees at the store who lack knowledge (not all LFS employees are this way, there are some true gems!) or well meaning family members spring finned gifts upon us... at some point, most of us will have been through/will go through a fish in cycle.
NEVER buy a fish purely to cycle a tank. All fish, regardless of their price tag, are living beings and deserve to be treated and respected as such. It is YOUR RESPONSIBILITY to ensure every fish under your care receives the best care possible. No fish is disposable.
Don't clean your filter (unless the flow is severely affected) or the tank during the cycle. If you are cycling fish in and have gravel substrate, vacuum lightly throughout and as it establishes.
Should you have fish already, managing with close monitoring and daily water changes is the best route, especially with Goldfish as they produce huge amounts of waste. I'm sure many of us have been there, we trust employees at the store who lack knowledge (not all LFS employees are this way, there are some true gems!) or well meaning family members spring finned gifts upon us... at some point, most of us will have been through/will go through a fish in cycle.
NEVER buy a fish purely to cycle a tank. All fish, regardless of their price tag, are living beings and deserve to be treated and respected as such. It is YOUR RESPONSIBILITY to ensure every fish under your care receives the best care possible. No fish is disposable.
Don't clean your filter (unless the flow is severely affected) or the tank during the cycle. If you are cycling fish in and have gravel substrate, vacuum lightly throughout and as it establishes.
How do I maintain my cycle?
As the Nitrifying bacteria do not live in the water column, big water changes won't affect your cycle as there is no beneficial bacteria in the water column. So if your tank and tap pH match, you can perform large, regular water changes with no ill effects. If your tank and tap pH differ by more than 0.5, stick with 50% maximum changes (you can still perform them regularly, but not more than 50% at a time so as not to shock the fish).
Only rinse media in dechlorinated or old tank water. The chemicals in tap water will likely kill your cycle, Chlorine being the big one. This will ensure your cycle is held.
If you wish to remove or change your substrate, do it by no more than 25% a week as there is some bacteria on all surfaces of the tank, but the majority are in the filter media. Removing it all in one go can cause a bump in the cycle.
Only rinse media in dechlorinated or old tank water. The chemicals in tap water will likely kill your cycle, Chlorine being the big one. This will ensure your cycle is held.
If you wish to remove or change your substrate, do it by no more than 25% a week as there is some bacteria on all surfaces of the tank, but the majority are in the filter media. Removing it all in one go can cause a bump in the cycle.