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Q11186 - HOWTO: How to Cycle a Saltwater Aquarium By Mark Callahan, Mr. Saltwater Tank
Let's face it: you want instant gratification.

As soon as your box of aquarium supplies arrives from MarineDepot.com, you drop everything and begin fiddling with your new gear. And, once that last piece of equipment is set up, you'll be ready to add fish to your new tank, right?

Not so fast.

You've got one step left before you can add fish to your new aquarium: cycling the tank.

Cycling a saltwater aquarium involves growing lots of nitrifying bacteria to process fish waste. The formal name for this process is called the nitrogen cycle.

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Taking your tank through the cycling process is important as you'll need lots of bacteria to take toxic fish waste (called ammonia) and turn it into less toxic compounds (nitrite, nitrate). Add in fish too early and they won't survive the cycling process.

Growing the bacteria takes time so one key to cycling your tank is patience. I know you are pumped to get your tank stocked with fish, but you'll want to take it particularly slow here.


Live rock is filled with nitrifying bacteria. Buying enough live rock for your tank will likely provide enough bacteria to get the cycling process started in your aquarium. However, live rock is often shipped to your fish store with only a small amount of water (if any) in the box. This means a lot of the bacteria and other life forms on the rock will die off before you place the rock inside your tank. In other words, adding live rock in and of itself will not immediately make your tank ready to go. You'll have to wait for the dead and decaying life forms to be processed by the surviving nitrifying bacteria before you add any fish. This process can take days, weeks or even a month depending on the condition of the rock.

Fiji's Best Saltwater Aquarium Live Rock

If you want to speed up the cycling process, you can add some beneficial bacteria in a bottle. Examples include: These products add bacteria to your system that can help speed up the cycle time. Remember the key rule for cycling your tank: patience. Even if you add these products, you still need to test your tank parameters daily until the cycle is complete.

Prodibio BioDigest

How do you know when your tank is cycled and ready for fish?

Once ammonia and nitrite levels drop beneath .25 mg/mL, your tank will be ready for fish. When your nitrate levels begin to rise, you know your tank is close to completing the cycling process. Choose one small, strong fish, like a clownfish or a chromis, to acclimate to your tank. You only want to add one fish at a time. Adding several fish at once can lead to an ammonia spike that may kill your fish. Remember: patience!

If you notice the aforementioned water parameters rising after you add fish, perform a large water change and add more nitrifying bacteria from a bottle/vial (click here to see ideal reef tank parameters). If necessary, you can use Kordon AmQuel Ammonia/Chloramine Remover to detoxify the ammonia immediately. Within a few days, beneficial bacteria will grow and be able to handle the added waste produced by your new fish.

Make sure to closely monitor ammonia and nitrite levels as you add more fish to the tank. A good rule of thumb is to add fish no faster than one fish every two weeks. The slow addition of livestock to a new tank ensures your aquarium system will be able to handle the increased waste load from each new fish.

You're going to have your saltwater tank for a long time, so remember, be patient throughout the cycling process.

Kordon AmQuel Ammonia/Chloramine Remover

About the Author

There is a central theme in Mark's life: WATER. WATER. WATER.

Growing up in Tennessee meant trips to the local lakes and rivers on the family ski boat. Spring Break was always spent in Hawaii cruising the reefs and forever ingraining memories of the beauty of the ocean on his mind.

Mark's first tank was the typical goldfish bowl. 1 gallon of water, some multicolored gravel in the bottom, a plastic plant and 1 fish. Seeing his keen interest in fish, Mark's parents quickly upgraded him to a 10 gallon freshwater aquarium. When he turned 9, his father announced it was time to upgrade to "the real thing" - a 75 gallon saltwater tank.

Jump ahead 22 years, and Mark maintains a 235 gallon tank and mrsaltwatertank.com, a website dedicated to taking the confusion out of setting up and maintaining a saltwater tank.

Mark also is the creator and star of Mr. Saltwater Tank TV a web-based TV show that not only entertains audiences, but educates them as well.

Since starting Mr. Saltwater Tank TV in 2010, Mark has created over 200 Mr. Saltwater Tank TV episodes resulting in over 3,250,000 views worldwide. The show has attracted 10,000+ YouTube subscribers and 6,000 + fans on Facebook.

In addition to Mr. Saltwater Tank TV, Mark has authored and co-authored 4 books including The No-Nonsense Guide to Setting Up A Saltwater Tank Volume One and Volume Two, The Ultimate Guide to Saltwater Tank Cruise Control and The No-Nonsense Guide to Preventing and Curing Nuisance Algae Outbreaks. His writing also includes 5 authored or co-authored articles for international magazines such as Tropical Fish Hobbyist and Marine Habitat Magazine.

Public appearances include speaking at major fish trade shows - Marine Aquarium Expo and the Seattle Marine Aquarium expo. Mark will be speaking at the Marine Aquarium Conference of North America (MACNA) in September 2012.

Mark also takes Mr. Saltwater Tank TV on the road as he's covered major saltwater aquarium trade shows including Marine Aquarium Expo (MAX), Seattle Marine Aquarium Expo (SEAMAX), Marine Aquarium Conference of North America (MACNA), and Reefstock.

When he isn't traveling or working, Mark maintains a 235 gallon mixed reef tank and spends time with his wife, 2 yr old son and his pug named Bart.
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Approved Comments...
Helpful as always!! Thanks, Marine Depot! Approved: 8/27/2012
Mark,explains things on a down to earth level,you dont have masters degree to understand what he is saying.. Approved: 8/14/2012
Based on personal tests (free products from a fish club meeting) and articles on the subject, the added chemicals dont really do much. I think you should have mentioned that the traditional amount of time is at least 30 days. With chemicals, about 28 days. If you really want to speed up the cycle time, borrow someone elses rock or sand/gravel. Doing so will dramatically reduce the cycle time and potentially add beneficial critters. While it is possible to introduce negative critters, it is no more of a risk than buying fish/rocks from a fish store. I have done this with fresh water and noticed only a nominal cycle. While this technique does not encourage people to buy the chemicals, that is no excuss. My personal take is that if you are looking out for the buyer recommend products that help, and discourage those that do not, they will support your store to the end of time. Otherwise, you become no better than Petco. Approved: 8/14/2012
I enjoy Marks articles and his videos. I was disappointed to see he left off Dr. Tims products which I believe he used on his own tank. Approved: 8/14/2012
Article Details
Created on 8/13/2012.
Last Modified on 8/14/2012.
Last Modified by Dot Yuson.
Article has been viewed 16944 times.
Rated 8 out of 10 based on 38 votes.
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