new tank syndrome and the nitrogen cycle

New Tank Syndrome

Have you heard about something called, New Tank Syndrome? It’s a term that can strike fear in the studious budding new aquarium hobbyist and is the unfortunate downfall of many who didn’t know it existed. Let’s dig into what we know and don’t know about this unfortunate phenomenon that affects new saltwater aquarium owners.

Starting up a reef aquarium is exciting. You’ve got your lighting and filtration running and the tank is full of water. Now the fun of building the reef begins – right? Not so fast! Before you add hundreds or thousands of dollars of marine life to your tank, have you considered the biofilter? Without proper preparation your new aquarium will suffer from New Tank Syndrome, exposing aquatic life to harmful ammonia and nitrite. New Tank Syndrome is easily avoidable once you understand how biological filtration works.

Biofiltration 101

All marine life adds waste products to the aquarium. Ammonia is released directly from the fish’s gills. Complex organic matter such as dead algae, worms, and other debris is broken down into other substances including ammonia. Invert, flake, and frozen foods are digested and added to the ammonia load.

Ammonia is harmful to fish and invertebrates. Fortunately, a natural two-step process, called biological filtration, occurs in our aquariums. Biofiltration involves two types of nitrifying bacteria. In the first step, ammonia is converted to nitrite (also harmful), by ammonia-oxidizing bacteria. In the second step, nitrite is converted to nitrate, by nitrite-oxidizing bacteria.

In reef aquariums, nitrate is removed biologically by algae or converted to nitrogen gas by denitrifying bacteria living in the rock and sand. This process is called the nitrogen cycle because ammonia, nitrite, and nitrate are all important water parameters and forms of nitrogen and it is directly related to New Tank Syndrome.

In a mature aquarium, the nitrogen cycle runs continuously. Ammonia and nitrite levels are kept so low

nitrogen cycle and new tank syndrome
Creative Commons Wikipedia

they cannot be detected with aquarium test kits. But reaching this biologically balanced state does not happen overnight. It may take several weeks for the biological filter to become fully active. During this development phase, ammonia and nitrite can climb to dangerous levels. This condition is known as New Tank Syndrome. New Tank Syndrome frustrates many aquarists by delaying stocking or even harming aquatic life. We’ll explore several ways to reduce the chances of NTS. But first, we’ll take a closer look at the engine that drives the nitrogen cycle– nitrifying bacteria.

Demystifying Nitrifying Bacteria

Ask questions about biological filtration at fish shops or online and you’ll likely walk away more confused due to conflicting advice. That’s because much of the common knowledge about nitrifying bacteria is a combination of facts and fiction, woven into a variety of theories.. Let’s take a look at what we know is true about these bacteria.

  • Nitrifying bacteria are very delicate: False. The nitrifiers are not as fragile as once believed. They will survive long periods in dirty, low oxygen conditions. New evidence is proving they will also live a long time with no food. I knew a professor at the University of Georgia who routinely stored used damp aquarium gravel in buckets for months. When he needed to start up lab aquariums, the seasoned gravel started the biofilter very quickly. The nitrifying bacteria remained alive on the damp gravel.
  • Nitrifying bacteria are rare. False. Nitrifiers live in lakes, streams, bogs, reefs, oceans, and estuaries. They are also found in soil, drinking water storage tanks, and sewage. Nitrifiers can even ride through the air in droplets of mist.
  • Nitrifying bacteria can live in fresh or saltwater but not both. False. While some live only in freshwater or saltwater…some species thrive in both!
  • Nitrifying bacteria are hard to get started in aquariums. False. The truth is it is hard to stop them from growing. Everything they need to form an active biofilter is found in a typical aquarium. While not completely required, a lot of aquarists prefer to have filter media. Nitrifying bacteria form colonies on nearly every surface in the aquarium, including gravel, sand, rock, even aquarium glass. They will grow wherever conditions are right.

Secrets of Starting the Biological Filter

So if nitrifying bacteria are everywhere, really tough, and don’t need a lot of special conditions to thrive, shouldn’t it be easy to start a biological filter and eliminate NTS? Starting the biofilter is easy. Waiting for it to mature is the hard part. Novice aquarists, eager to build their reef, often stock the aquarium too quickly. This extends New Tank Syndrome and stresses the aquarium livestock. Nitrifiers are very slow growers compared to other types of bacteria. It can take four to six weeks for the biofilter to become fully functional. Let’s look at several ways to start the biological filter and see how they work.

new tank syndrome and nitrogen cycle chart of test results
Creative Commons – The Aquariumwiki

Typical development of the biological filter over time. Watch for the rise and fall of ammonia and nitrite as the biological filter matures. It can take up to six weeks in some cases.

Biofiltration the Old Fashioned Way

Long before aquarists knew about ammonia and nitrifying bacteria, they were setting up beautiful marine aquariums. 150 years ago early Victorian aquarists were keeping reef tanks with no thought about biological filtration. They just added natural seawater, gravel, mud, and a couple of fish and inverts. The nitrifiers entered the aquarium “by accident.” If the tank was not over-stocked or over-fed, the aquatic life survived while the biological filter developed. Back then it was a mystery why some new tanks failed. Now we understand NTS and can even monitor it with test kits. Today all you need is some “biological seed” material from an established aquarium. This could be an old filter cartridge or sponge. Some use aged gravel from another aquarium. Toss it into your new tank with a couple of hardy fish. Monitor ammonia and nitrite levels to see when they rise and fall to zero. Now a few more specimens. Slowly build the reef. All you need is time and patience.

Early victorian aquarium

 Fishless Cycling

Understand that nitrifying bacteria need ammonia and nitrite as their energy source. If you have a 1000 gallon tank with two clownfish and a 55-gallon tank with two clownfish, the biological filter is essentially the same size in both aquariums. The biofilter grows to the “food” level in the aquarium. The idea behind fishless cycling is to force-feed nitrifying bacteria ammonia, causing them to create large colonies before any marine life is added to the aquarium. There are several methods to do this but the basic idea is to set up the aquarium with everything except livestock. Seed the aquarium with live nitrifying bacteria by adding gravel or filter media from another aquarium. Despite what you may have read, nitrifying bacteria can survive when packaged correctly. There are several “instant” biological filter starter products that contain live nitrifiers and reduce NTS. Now follow these ammonia dosing guidelines.

  • Add a few drops of unscented ammonia at a time, until the ammonia is between 2 and 4 ppm on a test kit. Do not exceed 5 ppm ammonia. Make a water change if you do as it will slow the process down considerably.
  • After about five days, test ammonia and nitrite every other day. When the ammonia and nitrite levels are down to about 1 ppm, add more ammonia to bring the level to 2-4 ppm.
  • Test every other day. When the ammonia and nitrite both drop to about 1 ppm, add another dose of ammonia (2-4 ppm).
  • When the levels drop to zero, the aquarium is ready for fish and inverts. A partial water change is recommended to replenish the buffers that are used up during the cycling process.

The benefits of fishless cycling are that no aquatic life is exposed to ammonia or nitrite during the process. You will also have a fully active biofilter that will handle waste and reduce stress on your new livestock.

The Hybrid method

Not every reef aquarist wants to perform a fishless cycle or add dirty filter media from another aquarium. Most people want to see some marine life in their new tank right away, even if it is just a few fish or pieces of base rock. In this case, it is best to add a liquid biological filter starter when aquatic life is added to the tank. There is no advantage to adding the bacteria weeks ahead and waiting for the biofilter to develop. The nitrifiers must have ammonia and nitrite as food sources to become active. Add the aquatic life and bacteria at the same time. Monitor ammonia and nitrite to track the development of the biofilter. Do not over-feed or add more animals until the ammonia and nitrite fall to zero.

 Is It Possible To Eliminate New Tank Syndrome?

No matter which method you use, the biofilter will take several weeks to develop. There are no shortcuts. Ammonia and nitrite levels must rise and fall over several weeks. New Tank Syndrome only becomes a problem when the ammonia and nitrite levels rise out of control. The good news is your tank does not have to suffer through NTS. Just follow these guidelines and take your time… you will have success!






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