Cycling Your Tank, New Tank Syndrome, The Nitrogen Cycle, and You

With much excitement and anticipation, you started your first fish tank. Sadly now, a few weeks later disaster has struck. Fish have died and others are looking like they would prefer to die as soon as possible. Hopefully this care sheet can help you avoid the disappointment and feeling of failure.

Welcome to the hobby; you are experiencing New Tank Syndrome or NTS. Though obviously not a scientifically classified malady, this is a very real condition that many new fish keepers find themselves experiencing. In our experience we find NTS more common in freshwater tanks than marine tanks. The reason being that a hobbyist doing a saltwater set up is more familiar with the cycling of an aquarium and tends to follow the cycle more closely. Keep in mind that every new tank will undergo a "seasoning" process. This process is called the Cycle or the Nitrogen Cycle. NTS is typically the result of mistakes that have been made by an inexperienced fish keeper during this seasoning process. It is possible that the loss of fish in a brand new tank can be minimized or even totally avoided by understanding the concept of tank cycling and monitoring this process with the appropriate tests.

The root cause of NTS is almost always the addition of too many fish too soon, into an unseasoned tank. The natural human tendency is to want to get some flash and color going in our new tank as soon as possible. After all, that IS what we spent all of that money for right? Unfortunately, many times this first tank results in the death of many costly fish, a disappointed hobbyist, and quite often, disappointed parents. The good news is that there is hope. With a few simple steps you can get your tank back on the road to recovery and long-term success.

The best way to put NTS into perspective for you is to think of it as being similar to a human condition where a person with a weakened immune system will contract every disease that they come in contact with. Likewise your new fish are in such a state of stress that they will begin to contract every bug that comes along. Results can be symptoms ranging from pale listless fish who stop eating, to swollen bodies or eyes and strange looking spots and growths. You may or may not notice the appearance of reddish coloration around the gill areas or gasping for “breath”. Other fish will simply die without a single warning symptom.

The majority of the time, NTS is the direct result of a heavily loaded tank that is undergoing its initial cycling process. Other lesser causes can be attributed to specific mistakes such as a failure to use a water conditioner when setting up the tank or failure to provide the proper water parameters or temperature for a certain type of fish. For the purposes of this care sheet, we will focus on the most frequent problem of acute ammonia and nitrite poisoning. This is what is responsible for the gasping motions made by the fish as they have oxygen available but simply cannot process it into their bodies due to the effects of the poison on their gills. Depending on just how toxic the levels of ammonia and nitrites have reached, fish that survive this ordeal, will most likely have a diminished lifespan, due to the stressed and weakened immune system.

 

The Nitrogen Cycle.

One of the most important things to understand in the successful keeping of an aquarium is the nitrogen cycle. The nitrogen cycle is responsible for the biological filtration within the system. The nitrogen cycle is the biological process that converts ammonia into other, relatively harmless nitrogen compounds. Several species of bacteria do this conversion for us. Nitrosomonas bacteria feed on both oxygen and ammonia, and with their biological activities, they excrete a chemical called nitrite. Although nitrite is not as toxic as ammonia, even at low concentrations in the aquarium, it can be harmful to fish and invertebrates. The other bacteria, Nitrobacter, which also utilizes oxygen, acts in a similar way as Nitrosomonas, and essentially changes the nitrite into a relatively harmless chemical called nitrate. The bacteria that will feed on nitrates are anaerobic, meaning they grow in areas of little or no oxygen. They require low-oxygenated stagnant water, and can be found in more elaborate filtration systems and within live rock. Here they breakdown the nitrates into free nitrogen. Cycling the tank refers to the process of establishing bacterial colonies in the filter bed that convert ammonia -> nitrite -> nitrate.

 

The nitrogen cycle in new aquariums

Newly setup aquariums lack the colonies of bacteria that are necessary to perform the biological filtration. Because of this, the aquarium must be cycled. Cycling refers to the process of establishing and maturing the biological filtration. In order to establish the system, we need to provide a source of ammonia for the Nitrosomonas bacteria in the filtration system so they can live, reproduce, and colonize. There are various opinions on ways to provide an ammonia source. Some feel that it is best to add a few hardy fish that can withstand the presence of ammonia and nitrites. Than you seed the aquarium with bacteria. Bob 's Feathered Friends Inc. offers products such as Cycle, BioZyme, StressZyme that you can seed the aquarium with.

As the fish in the new system are fed and begin to thrive, they will, through their biological activities, produce ammonia. The Nitrosomonas bacteria will begin to feed upon that ammonia and will start populating the aquarium. At this point, because the numbers of bacteria are limited, they will not be able to convert all of the ammonia that is present in the system, so the ammonia levels will continue to rise. The ammonia level will eventually reach a peak and than suddenly start to decline as the nitrite-forming bacteria take hold. Because Nitrobacter bacteria don't even begin to appear until nitrite is present in significant quantities, nitrite levels will rise (as the built-up ammonia is converted), continuing to rise as the continually produced ammonia is converted to nitrite. Once the Nitrobacter bacteria take hold, nitrite levels fall, nitrate levels rise, and the tank is fully cycled.

Your tank is fully cycled once nitrates are being produced and ammonia and nitrite levels are zero. We recommend testing and charting the ammonia and nitrite levels at least every other day throughout the cycling process so you will know when the tank is cycled. The cycling process normally takes anywhere from 2-6 weeks. At temperatures below 70F, it takes even longer to cycle a tank. Nitrates, in low to moderate concentrations, are not toxic to fish and invertebrates. Nitrates, however, can serve as a nutrient source for bacteria and plant life, and be the cause of other problems in the aquarium, such as excess algae. In marine aquarium systems higher levels of nitrates can be detrimental to some corals, anemones, and invertebrates. Nitrate levels can be controlled by chemical filtration and partial water changes on a regular scheduled interval.

 

The nitrogen cycle in established aquariums

An established aquarium is one that the biological filtration has been matured. There are situations that affect the nitrogen cycle in established aquariums, such as: adding livestock; unnoticed death in the aquarium; overfeeding; medicating the aquarium; and system maintenance.

 

Adding aquatic life

The biological filter of an established aquarium has just enough bacteria to handle the biological load that is in the system at that time. When we add aquatic life to the system, we are increasing the amount of ammonia for the bacteria in the biological filter to metabolize. The bacteria begin to multiply to make up for the extra biological load. How high the toxins will become in the system depends on both the amount of aquatic life added and the size of the aquarium. If to much aquatic life is added at one time it is possible for the ammonia and nitrites to reach dangerous levels, resulting in aquatic life losses. It is important to minimize these levels by stocking the aquarium slowly over time, giving the biological filtration time to catch up to the load. There are situations where it may be advantageous to stock the aquarium at a faster rate then the biological filtration can handle. These situations include but are not limited to:

· Adding many aggressive fish at the same time: It is best to acclimate aggressive fish, such as Lake Malawi African Cichlids, of the same species at the same time. Doing this will allow the fish to set their own territories prior to one individual fish taking over the entire aquarium. What you want to do is monitor the ammonia and nitrite levels in the tank frequently. This way you can perform maintenance procedures to help alleviate any loss of aquatic life.

· Transferring aquatic life to a hospital tank: A hospital tank is typically a small aquarium with minimal filtration. Bob 's Feathered Friends Inc typically recommends a 10 gallon aquarium with a sponge filter. Levels of toxins must be monitored closely when any number of fish are added to this new system.

 

Unnoticed death in the aquarium

It is possible in many aquariums, such as freshwater planted and saltwater reef aquariums, to have an inhabitant perish in a place where it cannot be seen. When this happens decay will take place which places a large load on the biological filtration.

 

Overfeeding

All food that is added to the aquarium for the fish and invertebrates is consumed in a short period of time. After a few hours, any food that is left uneaten in the aquarium will begin to be broken down by the bacteria and fungi, resulting in ammonia added to the system. This ammonia in turn becomes part of the biological load and if the amount of decaying food is great enough, can cause an imbalance in the biological filtration. If the aquarium has been overfed, it is necessary to siphon out any uneaten food and to perform a 25% water change.

Medicating the aquarium
Many medications affect the ability of the bacteria to function in the biological filtration. Anti-bacterial medications act in the way the name describes, by killing many types of bacteria. Unfortunately, the biological filtration is bacteria-based, and will be affected by these medications. Other medications such as copper, antibiotics, and ich treatments will also affect the filtration in different degrees. It is important, when treating an aquarium, to closely monitor both the ammonia and nitrite levels and to perform water changes or chemical filtration when necessary.

System maintenance
Water changes and filter maintenance will both affect the biological filtration to some degree. When performing water changes, it is important that the replacement water is free of any toxic chemicals such as chlorine and chloromines. These chemicals can kill bacteria within the system. In some instances your source water may contain chemicals such as phosphates and copper which can have an adverse effect on various aquatic life. At Bob 's we prefer to use reverse osmosis water as our source water. If you don't have access to reverse osmosis water than we recommend you purchase any of our various liquid dechlorinators. Filter maintenance, if not done properly, can have a large effect on the biological filtration. Again, the beneficial bacteria responsible for the nitrogen cycle, populate in the greatest numbers where the water flow and oxygen content of the water are the highest. This is typically within the filter. When performing maintenance on the filter, it is ideal to leave the biological media untouched in order to preserve the bacteria. If there is no biological media within the filter, it is wise to change only 1/2 of the mechanical media at a time. The remaining media that is to be reused should be rinsed in water taken from the aquarium in order to preserve the bacteria colony.

 

Restoring the balance

It is important to monitor the level of toxins in your aquarium. If your tank has went through one of the scenarios listed above we would recommend testing at least the ammonia and nitrite in the aquarium for at least a few days. On an established tank with no visible signs of distress we recommend testing all water parameters on a weekly basis. If any level of ammonia or nitrites is detected than it is important to take action through partial water changes or toxin absorbing resins.

When performing water changes we recommend changing no more than 25% of the aquarium water at a time. Changing more than 25% can cause rapid changes in both temperature and pH, which can result in added stress. For that reason it is best to perform small water changes frequently (even daily) rather than performing large water changes at less frequent intervals. Also, it is ideal if the replacement water, commonly referred to as makeup water, be the same temperature as the aquarium, and has been aerated prior to adding it to the tank.