Cycling Your Tank
Some of the most frequent questions from new reefers involve the tanks initial cycle.
How long will it take for my tank to cycle? How do I know if the tank is cycled?
The first is an impossible question to answer.
The time required to cycle a tank depends heavily on the live rock used, and how it is handled by the store and yourself during setup. Newly imported rock will have more die off and may take longer to cycle, but you usually get much more life in and on the rock. Live Rock that has been at the store for awhile can cycle relatively fast because this die off has occurred in the store's tanks. Rock that is kept too long from the water when taking it home and setting up your tank can also have considerable die off.
It can take anywhere from days to months for a tank to cycle.
The second question is simple.
The only way to tell if your tank is cycled and safe to start adding livestock, is to test your water.
The cycle we refer to in our tanks is the nitrogen cycle.
To establish the bacteria which convert Ammonia to nitrites, a source of Ammonia must be added to the tank. Your live rock will provide the Ammonia to start your cycle. If using dry rock to start a tank you will need to "seed" it with some live rock and/or fish food to create the Ammonia to start your cycle. Once these bacteria start producing nitrites, the bacteria which convert nitrites into nitrates will start to multiply and once nitrates are available, the Nitrate converting bacteria will start to multiply.
1. Ammonia (NH3)
The waste from the biological processes of living organisms, and dead organisms decaying in the tank produce Ammonia. Ammonia is very toxic. Bacteria which colonize rock and sand surfaces use Ammonia as food and convert it into nitrite. Ammonia should always measure zero in a cycled tank. Old school aquarists may recommend using damsels or a hardy fish to start the cycle. There is no reason to add fish to cycle a tank. This causes unnecessary harm, illness and death. Live rock will supply enough Ammonia to start the cycle in your tank.
2. Nitrite (NO2)
Nitrite is slightly less toxic than Ammonia. These bacteria also colonize sand and rock surfaces and use nitrites as food and convert them into nitrates. Nitrites should always measure zero in a fully cycled tank.
3. Nitrate:
Nitrate (NO3) is relatively harmless. Nitrates tend to accumulate in the reef system if it is not setup correctly, or overfed. Fish can tolerate fairly high Nitrate levels, but most Corals and Invertebrates cannot. Nitrate accumulation will also lead to Algae problems. One way to control nitrates is to do large water changes and dilute the Nitrate levels. Deep sand beds and Nitrate reactors are other ways to process the Nitrate more naturally. Nitrates in a fully cycled reef tank should ideally remain at zero, but up to about 20ppm is acceptable for some more tolerant livestock. Higher levels will lead to issues with coral health and Algae growth in the tank.
4. Nitrogen:
Nitrates are processed by bacteria which convert the nitrates into harmless nitrogen gases which escape into the atmosphere. The bacteria that convert the nitrates only live in oxygen poor (anaerobic) areas of the tank. The best way to establish these Anaerobic areas is to include a sand bed that has sufficient depth and small particle size to restrict water flow in the lower areas of the bed.
Your tank can be cycled without endangering any tank inhabitants. The part of the cycle which converts Ammonia to Nitrate should always be finished before any livestock added. Ammonia is introduced with the live rock. The decaying life on the live rock will provide the food for Ammonia and nitrite consuming bacteria to colonize the rock. Livestock should never be added until it is verified that both Ammonia and nitrite have dropped to zero levels through the use of test kits. While the tank is cycling, you will measure an increase in Ammonia and then it will begin to drop as Ammonia consuming bacteria start to grow. You will then see an increase in nitrites as the Ammonia gets converted to nitrite. As the nitrite consuming bacteria start to grow, the nitrite level will start to fall. When both Ammonia and nitrite levels fall to zero the cycling is complete. The nitrates will be high at this point and you should start your water changes now.
Once the bacteria have been established, the number of bacteria will always vary depending on the bio load of the system. It is important even in established tanks to increase the bio load of the system slowly so that the bacteria colonies can grow to match the load of the system. If too many fish are added to a cycled tank, the sudden increase in waste products will cause a new cycle to start. Livestock in the tank are at risk of illness and death from the Ammonia and nitrite spikes that will occur.
Ammonia chemically burns the surface areas of a fish's eyes, fins and gills, which causes the protective mucus from these surfaces to be removed. This leads to external and/or internal bacterial infections. Nitrites travel through the blood system, poisoning the fish.
Please do not use live fish to cycle your tank. There is no need to do this. It is cruel and completely unnecessary.
Copied from Michigan Reefers - http://www.michiganreefers.com/forums/new-hobby/90592-tank-cycle-information.html
Posted by - DLBerlin
Some of the most frequent questions from new reefers involve the tanks initial cycle.
How long will it take for my tank to cycle? How do I know if the tank is cycled?
The first is an impossible question to answer.
The time required to cycle a tank depends heavily on the live rock used, and how it is handled by the store and yourself during setup. Newly imported rock will have more die off and may take longer to cycle, but you usually get much more life in and on the rock. Live Rock that has been at the store for awhile can cycle relatively fast because this die off has occurred in the store's tanks. Rock that is kept too long from the water when taking it home and setting up your tank can also have considerable die off.
It can take anywhere from days to months for a tank to cycle.
The second question is simple.
The only way to tell if your tank is cycled and safe to start adding livestock, is to test your water.
The cycle we refer to in our tanks is the nitrogen cycle.
To establish the bacteria which convert Ammonia to nitrites, a source of Ammonia must be added to the tank. Your live rock will provide the Ammonia to start your cycle. If using dry rock to start a tank you will need to "seed" it with some live rock and/or fish food to create the Ammonia to start your cycle. Once these bacteria start producing nitrites, the bacteria which convert nitrites into nitrates will start to multiply and once nitrates are available, the Nitrate converting bacteria will start to multiply.
1. Ammonia (NH3)
The waste from the biological processes of living organisms, and dead organisms decaying in the tank produce Ammonia. Ammonia is very toxic. Bacteria which colonize rock and sand surfaces use Ammonia as food and convert it into nitrite. Ammonia should always measure zero in a cycled tank. Old school aquarists may recommend using damsels or a hardy fish to start the cycle. There is no reason to add fish to cycle a tank. This causes unnecessary harm, illness and death. Live rock will supply enough Ammonia to start the cycle in your tank.
2. Nitrite (NO2)
Nitrite is slightly less toxic than Ammonia. These bacteria also colonize sand and rock surfaces and use nitrites as food and convert them into nitrates. Nitrites should always measure zero in a fully cycled tank.
3. Nitrate:
Nitrate (NO3) is relatively harmless. Nitrates tend to accumulate in the reef system if it is not setup correctly, or overfed. Fish can tolerate fairly high Nitrate levels, but most Corals and Invertebrates cannot. Nitrate accumulation will also lead to Algae problems. One way to control nitrates is to do large water changes and dilute the Nitrate levels. Deep sand beds and Nitrate reactors are other ways to process the Nitrate more naturally. Nitrates in a fully cycled reef tank should ideally remain at zero, but up to about 20ppm is acceptable for some more tolerant livestock. Higher levels will lead to issues with coral health and Algae growth in the tank.
4. Nitrogen:
Nitrates are processed by bacteria which convert the nitrates into harmless nitrogen gases which escape into the atmosphere. The bacteria that convert the nitrates only live in oxygen poor (anaerobic) areas of the tank. The best way to establish these Anaerobic areas is to include a sand bed that has sufficient depth and small particle size to restrict water flow in the lower areas of the bed.

Your tank can be cycled without endangering any tank inhabitants. The part of the cycle which converts Ammonia to Nitrate should always be finished before any livestock added. Ammonia is introduced with the live rock. The decaying life on the live rock will provide the food for Ammonia and nitrite consuming bacteria to colonize the rock. Livestock should never be added until it is verified that both Ammonia and nitrite have dropped to zero levels through the use of test kits. While the tank is cycling, you will measure an increase in Ammonia and then it will begin to drop as Ammonia consuming bacteria start to grow. You will then see an increase in nitrites as the Ammonia gets converted to nitrite. As the nitrite consuming bacteria start to grow, the nitrite level will start to fall. When both Ammonia and nitrite levels fall to zero the cycling is complete. The nitrates will be high at this point and you should start your water changes now.
Once the bacteria have been established, the number of bacteria will always vary depending on the bio load of the system. It is important even in established tanks to increase the bio load of the system slowly so that the bacteria colonies can grow to match the load of the system. If too many fish are added to a cycled tank, the sudden increase in waste products will cause a new cycle to start. Livestock in the tank are at risk of illness and death from the Ammonia and nitrite spikes that will occur.
Ammonia chemically burns the surface areas of a fish's eyes, fins and gills, which causes the protective mucus from these surfaces to be removed. This leads to external and/or internal bacterial infections. Nitrites travel through the blood system, poisoning the fish.
Please do not use live fish to cycle your tank. There is no need to do this. It is cruel and completely unnecessary.
Copied from Michigan Reefers - http://www.michiganreefers.com/forums/new-hobby/90592-tank-cycle-information.html
Posted by - DLBerlin