Cycling a Saltwater Aquarium


Important First Notes:

A saltwater aquarium cycle should take no 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

When you've finished setting up your saltwater or reef aquarium you'll need to cycle it. First, please make sure to refer to our How To Start a Saltwater Aquarium page to make sure you have all the necessary equipment. If you don't have everything you need set up before you begin to cycle, 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). 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 can not stress the importance of a quality substrate and live rock enough. 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:

When you first start cycling your tank you should purchase test kits for ammonia, nitrite and nitrate. You should be able to see each of these elements rise and then fall as the next one rises. At the end of your cycle you should have no detectable amounts of ammonia or nitrite, but your tank will usually always show a small amount of nitrate. This will happen as your beneficial bacteria establish throughout your cycle.

Next you may ask how you acquire this bacterium though. The recommendation I am going to make, if you follow any of this advice, it is at your own risk and you agree to not hold is responsible for any outcome that should occur... here's why. It is very important to support your LFS (local fish store). One of the quickest ways to add beneficial bacteria to your aquarium is by acquiring sand or rock from an already established tank. BUT, you want to make sure your rock or sand comes from a reputable source or it can potentially harm your tank by introducing something to your tank that may cause future issues. Make sure to discuss with the LFS or tank owner if the tank has ever had any issues.

We believe the live rock or live sand method is the best way to cycle a tank. There are a lot of people that recommend using "cycle fish" also known as damsel fish. Thing is that this too is rather unfair to the fish. It is extremely stressful to the fish and not necessary to subject a living critter to those conditions when there are other options that are just as good. Plus, it can be rather difficult to remove the fish from your tank at a later point.

Timeframe & Algae Blooms

Onto timeframe. When cycling a tank there is absolutely no way to speed it up. There's dozens of products on the market that claim to speed up or even eliminate tank cycling. We wouldn't use any of these products and that's just personal preference. It's common biology that bacteria takes time to develop and there is no substitute for time. At MINIMUM a tank should take 5-6 weeks to cycle before it is ready for any actual animal life. Please be responsible when cycling a tank and your tank should reward you for years to come.

Most people notice either a light dusting of what looks like brown powder (diatoms), green "hair-like" algae (bryopsis) or a rust/red colored "slime" type algae (cynobacteria). All of these algae are completely normal and will usually disappear with time as your water chemistry improves. The majority of the time that a problematic algae pops up it's due to an excess of any number of harmful nutrients in your aquarium, including Nitrates, Phosphates and several others. As your tank ages and becomes more reliant upon it's own natural filtration these nutrients should be consumed by other beneficial tank members, which causes problematic algae to disappear. 

Should you have any further questions feel free to contact us and we will happily help with additional information to help ensure every tank achieves success. For more information about water chemistry and parameters please visit our Water Chemistry Page.

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