The Nitrogen Cycle
Giving your aquatic animals a happy life involves more than just proper nutrition; their overall life expectancy and quality of life is dictated by the conditions of the water they call home. Before embarking on any quest to care for both freshwater and saltwater-dwelling animals, an understanding of the overall idea of the nitrogen cycle is key.
Steps of the Nitrogen Cycle in an Aquarium
Food
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Animals ingest food
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Animals produce waste
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Leftover food and waste turn into sources of decomposing matter
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Decomposing matter releases Ammonia
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Ammonia is consumed by bacteria that converts ammonia to nitrites
(Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus)
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Nitrites are produced
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Nitrites are consumed by bacteria that converts nitrites to nitrates
(Nitrobacter, Nitrospina, and Nitrococcus)
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Nitrates are produced
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Nitrate reduction can be done through filter media or carbon additives, aside from live rock
(Note: I will update this section as I discover more effective methods to reduce nitrate levels without having to resort to water changes.)
Other Things to Consider
Purchase a saltwater test kit such as the API Saltwater Master Test Kit to test for the pH, ammonia, nitrite, and nitrate levels of the water, as well as separate tests to measure the Calcium and Phosphate levels, once your aquarium has completed or is nearing completion of the nitrogen cycle. API doesn’t always carry a complete range of test kits, but I’ve had accurate results using their test kits, aside from their being readily available at most pet stores. Some tests like Phosphate, are not always stocked by your local fish or pet store, and in such a case, I have to default to ordering them online. I once ordered a Salifert (Dutch) test kit through Amazon, but the test kit was most likely expired, as the yields kept producing a zero reading for ammonia, when I knew it was not. I highly recommend sticking to purchasing test kits from brick and mortar stores. At the initial phase, I had to test the water twice a day to watch out for any changes in ammonia levels, but as time went on and nitrifying bacteria took up residence, ammonia and nitrite levels slowly lowered to the point that I could skip days without taking readings. Once your aquarium’s nitrogen cycle has been established, it won’t be necessary to test frequently, as your goal is to allow the aquarium to be self-sustaining in the long-run. For me personally, I like to do tests at least once a week, but in reality, I could go up to two weeks or more, without testing.
Setting up an aquarium should be done prior to acquiring livestock, but it is possible to complete the nitrogen cycle with livestock already added. It is a risky take, but it is possible, and expect to lose several nights of sleep, until your aquarium’s parameters have been stabilized.
Do not obsess over test level readings. While ammonia, nitrite, and nitrate levels read zero in the ocean and are the most ideal conditions that should be emulated, data shows that it is more important to keep these levels as close to zero as possible, and not in constant in fluctuation.
Ammonia and nitrite levels should be zero, in order to give your animals the best possible chance of living their full lives, but nitrate levels on the other hand can be tolerated much better. The exact value of nitrate readings is in flux (with some aquarists claiming that their livestock live happily even at levels up to 20 ppm!), but to play safe, readings should go no more than 5.0 ppm.
Use a frag (i.e. a single coral fragment broken off from a coral colony) to gauge the conditions in your aquarium, especially during the first stages of setting up the aquarium. Think of it as an analog to the canaries used in coal mines to detect the presence of carbon monoxide.
Bottled bacteria is the most important aspect of establishing a healthy nitrogen cycle and ecosystem for your livestock. Instant Ocean’s BIO-Spira® managed to lower the ammonia within a day after adding it into my aquarium. Although not necessary, the traditional method in establishing a healthy nitrogen cycle and ecosystem involves the use of live rock and an aged filter from another aquarium, but this process can take at least a year to establish itself.
Do not buy your bottled bacteria from Amazon. Storage conditions in warehouses could have gone high enough to the point that the bacteria in the bottle was killed off. Stick to your local pet or fish stores or through buying directly from the manufacturer’s website (wherein they take care to ship their products with cold packs, depending on the time of the year). Because of this, I had no such luck with FritzZyme® 9 Saltwater’s live nitrifying bacteria, as it was sold by Amazon. I tried two bottles but doses from both bottles both did nothing to lower the ammonia levels in my aquarium; only a locally-bought nitrifying bacteria-in-a-bottle such as Instant Ocean’s BIO-Spira® did the trick.
Aside from corals and livestock, watch your live rock closely for the stages of algae that appear. This is a metric stick for determining the health of your aquarium and the stage that it could be at.
Before adding any nitrifying bacteria to the water, test the solution first to be certain that only ammonia is present, and not nitrite nor nitrate. This means that you’ll need enough of the bacterial solution to dose your aquarium with, even if you subtract some for testing. Ammonia is added to the bottle of the beneficial bacteria to serve as a food source to keep them alive, so, high levels of ammonia are to be expected. One unfortunate aquarist however, posted a review on Amazon, stating that the bottle of nitrifying bacteria that he purchased, contained high levels of nitrite instead, which became responsible for the death of his animals, only finding out when it was too late. It is good practice to test any bacterial solution or water prior to adding it into your aquarium, and can spare the lives of your animals.
Do not overstock your aquarium with animals. The following are two major reasons not to:
For every animal / livestock added, consider that this equals waste and waste means more ammonia is produced. Plan accordingly.
Be sure to note that some species of animals can need more room than others. Overstocking an aquarium can lead to a lower quality of life for, not just the new resident, but also for the rest of the animal inhabitants living in the aquarium.
Special thanks to:
Anthony for the note on the basics of the nitrogen cycle and for the filter floss