Cycling a Saltwater Aquarium


Important First Notes:

A saltwater aquarium cycle should take not less than 6 weeks.

There is NO WAY to speed this is up, no chemical. This is a biological process.

Everyone who is starting to cycle an aquarium should have a good set of test kits around to keep an eye on what their tank is doing. We recommend the Salifert brand. We've been using their tests for decades and we're always impressed by their accuracy and lower cost. Ammonia, Nitrite, and Nitrate are 3 must have tests. As your tank moves further into the cycle you'll be able to watch your nitrogen cycle at work.

Cycling a Tank

The very first thing you'll need to do, well, after setting up your tank and purchasing all necessary equipment, is called "cycling" your tank. If you have any questions concerning exactly which equipment you may need you can refer to our Starting a Saltwater Aquarium (click HERE) page. If you don't have everything you need set up before you begin to cycle aquarium, you might have to start all over. Adding parts as you go can potentially throw your tank into a new cycle.

You'll want to make sure you have a good quality salt, sand, and your rock (if you're building a reef tank). At we only use AquaForest Reef Salt. It's the best salt we've ever tested when it comes to maintaining stable levels of calcium and magnesium. Caribsea makes an amazing live sand product that comes in many shapes and colors. They are one of the most trusted names in the aquarium industry based on a very well deserved reputation. You'll want to mix your salt and get your specific gravity to a safe level, as well as your temperature before you add the live sand. The reason being is you don't want to spend all that money on beneficial bacteria sand only to kill it off by having salinity or temperature fluctuations.

Here we cannot stress enough the importance of a quality substrate and live rock. It allows for the colonization of aerobic and anaerobic bacteria that maintains your nitrogen cycle. This is when your tank turns ammonia to nitrite then nitrite to nitrate which is then removed from your tank via numerous methods. Even the smallest amount of nitrate can be harmful to more sensitive tank members.

General Specifics for Properly Cycling a Saltwater Aquarium:

  • Specific Gravity: 1.022 - 1.026
  • Temperature: 78 - 82 degrees Fahrenheit.

Important Testing Information:

You'll want to make sure you use quality test kits from brands such as Salifert when you first begin cycling your tank. Seachem also makes an Ammonia Meter that usually comes in very helpful. You should at minimum have a nitrate test kit handy to make sure your nitrogen cycle has run it's course and your aquarium is converting Ammonia to Nitrite and then Nitrite to Nitrate. Given time, your aquarium will colonize larger amounts of beneficial bacteria so it's able to process Nitrate as well and remove it from your tank; this is the end of nitrogen cycle when this begins occuring. Ideally your Nitrate levels should be zero, however some tanks will always have smaller levels of nitrate.

A lot of people call to ask us "How to begin to colonize beneficial bacteria in our tank to start the nitrogen cycle?". And our answer is something that we recommend following at your own risk, as in if you do it and it harms your tank, it's not our fault. One of the fastest ways we have seen to start and establish beneficial bacteria in a new aquarium is to purchase live rock or sand or what's known as Damsel Fish from your local fish store. Please make sure you are purchasing your live rock or sand from a reputable source. You don't want to get something in your tank that hitchhikes in some live rock such as Aiptasia for example. Damsel Fish, if you choose this method please make sure that you can get them out and take them back to your fish store once your tank is established. Damsel Fish get quite large and are extremely aggressive.

Live SAND is usually the best way to go. Some cycle products actually do work. They won't cut down on time it takes to get to the safety point for keeping living critters in your tank, but they can be helpful at getting the cycle started. As we stated at the beginning, there is absolutely no way to cut down on a safe amount of time to begin adding livestock to your aquarium. It simply a balance of bacteria and time that it takes to be able to have a tank that can support life. We DO water testing here as well should you ever have any tank issues. We do get a large number of questions when it comes to reef tanks as well, since we have two staff members that have been marine biologists for over 20 years.

What is my tank doing and why?

Cycles take time. At MINIMUM no life should be added to a tank inside of 7-8 weeks unless it is something like a handful of snails or cycle fish. IF you are using live animals, please do not add them until you've established even a smaller amount of bacteria by using live rock or sand. Here we believe it is inhumane to add any life to a tank that has been up less than a few weeks. PLEASE start with using live rock or live sand to begin building beneficial bacteria.

At the beginning of your cycle you won't notice many changes then all the sudden a couple weeks in BOOM, it will look like brown dust is covering everything. No, you didn't do anything wrong LOL This is the first algae bloom your tank will have it's an algae called "Diatoms". This is a healthy stage as it is only able to form diatoms because your tank is beginning to support beneficial bacteria. Second you may get a green hair-like algae known as Bryopsis or a red/rust colored algae known as cyanobacteria. These changes are completely normal and for the most part even healthy because it means your water parameter are moving along in the cycle. Most of the time when one of these algae pop up it's due to an excessive amount of nutrients in your tank such as nitrite, nitrate or phosphate. As your tank builds its ability to break down these harmful chemicals, the algae itself will usually become less of an issue.

Both bryopsis and cyanobacteria can become a problem if they grow in excess down the road though, so make sure to read up on what they are and how to manage them.

Please head to our Algae In Your Aquarium page if you have any questions about what these algae are and how to rectify them.

If you need further assistance we are usually very about replying to emails because we want to help ensure that every tank thrives to protect the life going into it. Just click the "contact us" link above to ask any questions you might have about Saltwater Tank Cycling.

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