texdoc77
New member
Recently I have seen a ton of questions about tank cycling. Questions such as, "œIs my tank cycled?" or "œHow do I cycle my tank?" have been asked over and over. I wanted to take a couple of minutes and break this down for those that are new. It's actually pretty straightforward once you understand the biology of tank cycling.
What is Tank Cylcing?
First let's discuss exactly what we are talking about when we say tank "œcycling". For our purposes we are talking about establishing bacterial colonies for the denitrification of ammonia and nitrite. This means that we have established a bacterial base to convert ammonia into nitrite and then into nitrate. I have also seen the phrase tank "œcycling" with other aspects of tank maturity. For example a new tank has lots of silicates which cause diatom blooms, also a new tank can leach phosphates from new rocks which causes significant algae growth. While this is part of overall tank maturation, it is not the cycling of a new tank we are discussing here.
How does this happen?
For this to happen two bacteria groups are necessary. First, the "œNitrosomonas" group oxidizes ammonium into nitrite, then that nitrite is further oxidized by the "œNitrobacter" group into nitrate. Both of these groups of bacteria, also called a genus, live ubiquitously within the environment. This means that these bacteria basically live everywhere and are constantly denitrifying ammonium within the environment.
Why is this important?
Ammonia and nitrite are very toxic to fish even at low levels. Nitrate is also bad for fish, but it takes quite a bit more to harm them. This allows us time to export the nitrate through water changes, skimming and carbon dosing. But thanks to our Nitrosomonas and Nitrobacter bacteria, once established, they take the most harmful parts of the equation out of the tank.
So how do I cycle my tank?
Add Ammonia: There are many ways you can begin the cycling of a tank, but really what you are doing is adding ammonia. Ammonia is basically the food of the Nitrosomonas bacteria and anywhere in nature where ammonia build up occurs these bacteria will begin to become active and multiply in great numbers. There are many ways in which we can add ammonia to our tanks, but for our purposes I will discuss the most common. Many people simply throw a raw shrimp in the tank. As the shrimp decomposes ammonia is released. You can also "œghost feed" the tank and as the food breaks down ammonia is released. Finally, you can directly add ammonia either from a pure source or a kit designed for the purpose of tank cycling. I bring up one other method for the express intent to denounce it. In the past it has been common to add fish to a tank and the fish waste would add the ammonia and help the tank begin the cycle. It is my personal opinion that this is a cruel thing to do the fish and is almost universally frowned upon in the saltwater hobby.
Provide Substrate: The bacteria also will need a substrate, or someplace solid to live. This is where rock, sand, rubble and other media come into play. All these provide surface area for the bacteria to grow on and multiply. A traditional tank may only need about a pound of live rock per gallon and then 1-2" of sand to act as substrate. Others may choose to go with less live rock and add media in the refugium to help.
Test often: Finally, you will want to have a good test kit to measure the ammonia, nitrite and nitrate. A good way to do this is to add ammonia and begin testing ammonia and nitrite daily. Once you see the ammonia begin to go down, you should see an increase in nitrite. Then you should see the nitrite decrease and a subsequent increase in nitrate.
Can't I just add live rock?
Of course, that is a great idea. You can add just a few pieces to get the bacteria introduced and give you a jump start. You will still want to have a source of ammonia to keep the colonies of bacteria you are introducing alive and to help grow more in other parts of your tank, like the sand, other "œdead" rock and rubble in the refugium. Of course the more live rock you add to the tank the quicker the bacteria will reach levels where they keep the ammonia and nitrite at zero. You could even add so much that the tank does not really cycle at all, but already has enough colonies of bacteria to sustain whatever livestock you wish to start with. Most people would not purchase that much live rock as it is expensive, but could be feasible if you were downsizing to a smaller tank and had excess live rock.
How long does it take to cycle?
This also depends on how you decide to cycle the tank. For many they simply add ammonia in the manner they prefer then let nature take over. This can take several days to a couple of weeks for the initial bacterial group, Nitrosomonas, to become active and begin converting ammonium to nitrite. Once nitrite levels get high enough the next
bacterial group, Nitrobacter, then begins to become active and multiply. This usually takes between 4 and 6 weeks. You can also speed up the process by adding solutions that already contain some of the bacteria. Still, however, most tanks won't be cycled for about three weeks. The caveat is the discussion of live rock above.
How do I know when my tank is fully cycled?
Basically once you actually start getting nitrate and no longer have any ammonia or nitrite you are fully cycled. What this means is that any new ammonia should be processed by the bacteria into nitrate relatively quickly. If you are still testing positive for ammonia or nitrite, the cycle is not yet complete. You can make sure after your ammonia and nitrite levels have zeroed out by adding enough ammonia to get to 2ppm and then making sure the levels decrease to zero in a short period of time, such as overnight or 24 hours.
So when do I add fish?
Once the tank is fully cycled add a couple of fish. They will then produce ammonia via their waste and will "œfeed" the bacterial colonies you have grown with your cycling process. Over the next few days the number of bacteria will grow to accommodate the amount of waste your fish are producing. Remember bacteria are living and their population will only grow as large as the food source. This is why you go through "œmini-cycles" when you add new fish. Adding new fish creates more ammonia than the bacteria are used to handling. For a short time the ammonia levels rise until the Nitrosomonas bacteria multiply. Once those bacteria increase their numbers enough to deal with the new ammonia more nitrite begins to be produced and the Nitrobacter bacteria increase . This "œmini-cycle" is safe as long as you do not add too much at once. You should allow your bacteria time to catch up quickly and keep the ammonia and nitrite spikes relatively low. I recommend waiting about a month in between adding new fish. However, if you are impatient (well, this may not be the hobby for you) and testing ammonia, nitrite and nitrate daily and get back to zero ammonia and nitrite, it is probably safe to add more livestock at this point.
What about coral?
I think it is a good rule of thumb to add livestock to your tank slowly for a lot of reasons, not just for ammonia spikes. Coral do add to the bioload, as does everything, but of course not nearly as much as fish. I think you are safe adding a few coral at a time as well, of course you will want to be adjusting your calcium and alkalinity levels for the new coral.
Are there bacteria that convert nitrate?
Yes, and many people use carbon dosing to keep this particular type of bacteria at levels that helps to process the nitrate. However, this is not part of the traditional cycling of the tank and can be learned about elsewhere.
What is Tank Cylcing?
First let's discuss exactly what we are talking about when we say tank "œcycling". For our purposes we are talking about establishing bacterial colonies for the denitrification of ammonia and nitrite. This means that we have established a bacterial base to convert ammonia into nitrite and then into nitrate. I have also seen the phrase tank "œcycling" with other aspects of tank maturity. For example a new tank has lots of silicates which cause diatom blooms, also a new tank can leach phosphates from new rocks which causes significant algae growth. While this is part of overall tank maturation, it is not the cycling of a new tank we are discussing here.
How does this happen?
For this to happen two bacteria groups are necessary. First, the "œNitrosomonas" group oxidizes ammonium into nitrite, then that nitrite is further oxidized by the "œNitrobacter" group into nitrate. Both of these groups of bacteria, also called a genus, live ubiquitously within the environment. This means that these bacteria basically live everywhere and are constantly denitrifying ammonium within the environment.
Why is this important?
Ammonia and nitrite are very toxic to fish even at low levels. Nitrate is also bad for fish, but it takes quite a bit more to harm them. This allows us time to export the nitrate through water changes, skimming and carbon dosing. But thanks to our Nitrosomonas and Nitrobacter bacteria, once established, they take the most harmful parts of the equation out of the tank.
So how do I cycle my tank?
Add Ammonia: There are many ways you can begin the cycling of a tank, but really what you are doing is adding ammonia. Ammonia is basically the food of the Nitrosomonas bacteria and anywhere in nature where ammonia build up occurs these bacteria will begin to become active and multiply in great numbers. There are many ways in which we can add ammonia to our tanks, but for our purposes I will discuss the most common. Many people simply throw a raw shrimp in the tank. As the shrimp decomposes ammonia is released. You can also "œghost feed" the tank and as the food breaks down ammonia is released. Finally, you can directly add ammonia either from a pure source or a kit designed for the purpose of tank cycling. I bring up one other method for the express intent to denounce it. In the past it has been common to add fish to a tank and the fish waste would add the ammonia and help the tank begin the cycle. It is my personal opinion that this is a cruel thing to do the fish and is almost universally frowned upon in the saltwater hobby.
Provide Substrate: The bacteria also will need a substrate, or someplace solid to live. This is where rock, sand, rubble and other media come into play. All these provide surface area for the bacteria to grow on and multiply. A traditional tank may only need about a pound of live rock per gallon and then 1-2" of sand to act as substrate. Others may choose to go with less live rock and add media in the refugium to help.
Test often: Finally, you will want to have a good test kit to measure the ammonia, nitrite and nitrate. A good way to do this is to add ammonia and begin testing ammonia and nitrite daily. Once you see the ammonia begin to go down, you should see an increase in nitrite. Then you should see the nitrite decrease and a subsequent increase in nitrate.
Can't I just add live rock?
Of course, that is a great idea. You can add just a few pieces to get the bacteria introduced and give you a jump start. You will still want to have a source of ammonia to keep the colonies of bacteria you are introducing alive and to help grow more in other parts of your tank, like the sand, other "œdead" rock and rubble in the refugium. Of course the more live rock you add to the tank the quicker the bacteria will reach levels where they keep the ammonia and nitrite at zero. You could even add so much that the tank does not really cycle at all, but already has enough colonies of bacteria to sustain whatever livestock you wish to start with. Most people would not purchase that much live rock as it is expensive, but could be feasible if you were downsizing to a smaller tank and had excess live rock.
How long does it take to cycle?
This also depends on how you decide to cycle the tank. For many they simply add ammonia in the manner they prefer then let nature take over. This can take several days to a couple of weeks for the initial bacterial group, Nitrosomonas, to become active and begin converting ammonium to nitrite. Once nitrite levels get high enough the next
bacterial group, Nitrobacter, then begins to become active and multiply. This usually takes between 4 and 6 weeks. You can also speed up the process by adding solutions that already contain some of the bacteria. Still, however, most tanks won't be cycled for about three weeks. The caveat is the discussion of live rock above.
How do I know when my tank is fully cycled?
Basically once you actually start getting nitrate and no longer have any ammonia or nitrite you are fully cycled. What this means is that any new ammonia should be processed by the bacteria into nitrate relatively quickly. If you are still testing positive for ammonia or nitrite, the cycle is not yet complete. You can make sure after your ammonia and nitrite levels have zeroed out by adding enough ammonia to get to 2ppm and then making sure the levels decrease to zero in a short period of time, such as overnight or 24 hours.
So when do I add fish?
Once the tank is fully cycled add a couple of fish. They will then produce ammonia via their waste and will "œfeed" the bacterial colonies you have grown with your cycling process. Over the next few days the number of bacteria will grow to accommodate the amount of waste your fish are producing. Remember bacteria are living and their population will only grow as large as the food source. This is why you go through "œmini-cycles" when you add new fish. Adding new fish creates more ammonia than the bacteria are used to handling. For a short time the ammonia levels rise until the Nitrosomonas bacteria multiply. Once those bacteria increase their numbers enough to deal with the new ammonia more nitrite begins to be produced and the Nitrobacter bacteria increase . This "œmini-cycle" is safe as long as you do not add too much at once. You should allow your bacteria time to catch up quickly and keep the ammonia and nitrite spikes relatively low. I recommend waiting about a month in between adding new fish. However, if you are impatient (well, this may not be the hobby for you) and testing ammonia, nitrite and nitrate daily and get back to zero ammonia and nitrite, it is probably safe to add more livestock at this point.
What about coral?
I think it is a good rule of thumb to add livestock to your tank slowly for a lot of reasons, not just for ammonia spikes. Coral do add to the bioload, as does everything, but of course not nearly as much as fish. I think you are safe adding a few coral at a time as well, of course you will want to be adjusting your calcium and alkalinity levels for the new coral.
Are there bacteria that convert nitrate?
Yes, and many people use carbon dosing to keep this particular type of bacteria at levels that helps to process the nitrate. However, this is not part of the traditional cycling of the tank and can be learned about elsewhere.
