How to Cycle Saltwater Aquarium

Posted by jared burbank on

Starting a saltwater aquarium is very different from starting a freshwater aquarium where you can set up the tank, add dechlorinator and immediately add fish, a saltwater aquarium has to be cycled before you can add fish. Cycling a saltwater aquarium is a process in which the water goes through several biological changes that results in it being chemically balanced to sustain life. It's a tedious process that usually takes about a month complete. But, it's necessary process to keep your marine life healthy and alive.


There are several different methods that you can use to cycle a new saltwater aquarium. However, no matter how you cycle your tank it's going to take some time and patience. Because all of the methods work, the one you should choose is a matter of personal preference.



What is a Cycling?


Ammonia is needed for the cycling process to succeed. It can be produced in several ways, but usually it comes from dead decomposing matter or fish waste. During the process bacteria converts the ammonia into nitrite and at various levels of the process these two chemicals reach toxic levels. If you have fish in the water during this time the levels are very harmful or lethal to fish. For this reason do not use live fish to cycle your aquarium.  This good bacteria need to be established in sufficient numbers before your aquarium can safely handle fish.


Cycle An Aquarium Using Live Rock


In my opinion the best way to cycle any new saltwater aquarium is with live rock and some sort of ammonia supply.  I prefer to use an uncooked shrimp from your local supermarket to supply that ammonia.  Start by filling your aquarium with salt water, add sand if desired, then your dry or live rock.  Dry rock is nice because it is cheaper than live rock but live rock will usually cycle your aquarium faster.  If you are starting with dry rock do include a piece or two of live rock because this will help to seed your dry rock with the bacteria you need.


Once you have everything in place then I like to throw in a raw deli shrimp to feed the cycle.  This piece of shrimp will decay and feed the bacteria. To start, the ammonia level will rise rapidly because you do not have the adequate concentration of the right types of bacteria. This is the first stage and the bacteria is beginning to be established.


After a number of days to a week or two, ammonia levels will continue to rise and reach its peak and begin to decline. Ammonia levels should decline rapidly as the first stage progresses and bacteria will then begin to convert it into the equally toxic nitrite.  Your Nitrite levels with continue to climb as the bacteria convert this ammonia.




After a week to a few weeks your nitrite levels should start to decline and your nitrate levels will start to climb.  This means the bacteria in your rocks are doing their job and establishing themselves.


Your bacteria are now established at this point of the cycle. It can keep up with the ammonia from your decaying shrimp, turning it into nitrite and then quickly converting it into nitrate.



Cycling An Aquarium With Fish Food


To cycle your tank using fish food you basically add food on a daily basis just as if you are feeding fish. This creates a constant decomposing process that produces ammonia. While this method does work it can take 6 weeks or more to complete the cycling process. And, it has several disadvantages. It can be difficult to create a large bacterial colony, you may get spikes in the levels of nitrites and ammonia and decaying food can produce other chemicals such as phosphates.


Cycling An Aquarium Using Ammonia


Using ammonia to cycle a tank can take from 3 to 6 weeks. You will literally be adding pure ammonia to the water. Make sure that you purchase unscented ammonia that doesn't contain any additives. Using a dropper, add from 3 to 5 drops of ammonia for every ten gallons of water on a daily basis. The goal is to maintain a level of 5 ppm. In the initial phase there won't be any nitrites in the water. Continue adding the ammonia and testing the water until it shows a nitrite reading.


After there is nitrites in the water reduce the daily dosages of ammonia to 2 to 3 drops for each 10 gallons of water. You will need to continue this regimen until both the nitrite and ammonia tests reach 0 ppm. Once you have the correct reading start reducing the temperature. You will also need to perform a major water change of around 90% and add some activated carbon to help remove any unwanted additives that may have been in the ammonia.




Cycle An Aquarium With Commercial Products


Today, there are various commercial products on the market that say they can accelerate the cycling process. Some of these products can say they have your tank ready to use in as little as 24 hours. Some contain a large quantity of bacteria while others consist of enzymes that can assist in helping bacteria to grow much faster. These concentrated forms of beneficial bacteria can be used to cycle a brand new saltwater aquarium and stabilize a tank after water changes but please test your water when using these products.  I have yet to personally see anything cycle a tank in 24 hours.



Your Tank is Cycled, what to do now?


Once your ammonia and nitrite levels reach 0 this means your cycle should be complete.  You should then preform a water change to bring your nitrates down (this is the only way to bring nitrates down).  You are also likely getting an algae bloom in your new tank and this is the time to add a clean up crew to your tank.  These are snails and or hermit crabs and will work to help keep your tank clean.  Once these are added and your and your tank remains stable then you can add a fish.  With a marine aquarium you want to add things slowly so your bacteria can keep up with your new inhabitants.  Adding things too quickly can cause another mini cycle and you don’t want to do that to your new fish.


Congratulations on your new marine aquarium and we hope you enjoy the benefits of having a little piece of the ocean in your own home.