Cycle a Saltwater Tank

While you may be excited to start your new saltwater aquarium, a full water cycle is needed first. Cycling the water is a chemical process that makes the water livable for fish by creating nitrates. There are two different ways of cycling the tank. You can do it without fish by adding ammonia to the water manually. You can also do it using a few hardy species of fish who will produce ammonia for you.

Steps

Cycling without Fish

1. Set up the tank before buying fish. Start setting up your saltwater tank about six weeks before you purchase any fish. This will give you plenty of time to cycle the tank. If you add fish to the tank before cycling the water, the fish will die.
   • Set up the entire tank before cycling the water. This includes installing the filter, skimmer, and hydrometer, mixing the water with salt mix, and adding decorations.
   • If you have already added fish, you must move them to an established tank that has already been cycled. If you do not have an established tank, you will need to follow the method for cycling with fish. Do not increase the temperature or add ammonia, as these steps will kill the fish.
   • Cycling the tank is not an exact process. It can take anywhere from between two to six weeks (or occasionally longer). This is because bacteria needs to grow in the tank for it to work, and this process happens naturally on its own.
2. Increase the temperature of your tank to produce bacteria. Raise the temperature of the water to {{safesubst:#invoke:convert|convert}}. This will encourage the growth of good bacteria and speed up the cycling process. You must remember to decrease the water temperature before you add fish.
3. Add ammonia to the tank to start the process. You will need a source of ammonia in the tank. Over time, ammonia will convert into nitrites and nitrates. There are many different ways to add ammonia. You only need to do one.
   • Cut up a piece of raw fish or shrimp. Add a one inch chunk to the tank. One piece usually does the trick. If ammonia levels are not rising after two weeks, you can add another.
   • Add just a few flakes of fish food every twelve hours. It is better to use a little bit at a time to avoid spiking ammonia levels.
   • Every day, add five drops of pure ammonia for every ten gallons in the tank. Once your test kits start detecting nitrites, reduce this to three drops a day.
   • If a friend has a saltwater tank that has already been cycled, you can take some gravel or filter rock from their tank, and place it in yours. Live rock taken from a coral may also work.
4. Test the water every day for ammonia. You will need an aquarium test kit that can detect the presence of ammonia, nitrites, and nitrates. Test the water every day for between two and six weeks. At first, you will want to bring the ammonia levels up to 2 parts per million (ppm). Keep testing until the ammonia levels suddenly drop down to 0 ppm.
   • Most test kits take a sample of water from the tank into a separate tube. You will add a special solution to the tube. When the water changes color, compare it to a special chart, which will tell you how much ammonia is in the water.
   • You can also use Ammonia Alert. This strip attaches to the inside of your aquarium. The meter on the strip will darken to show how much ammonia is present.
   • If you don’t have test kits, some fish or pet stores will test a sample of your water for a small fee.
   • If ammonia levels rise above 2ppm, stop adding it for a few days to let the cycle catch up. A partial water change can also help.
5. Start testing for nitrites after ammonia levels drop. Once ammonia levels drop, take the nitrite test from your kit, and start testing it every day. Keep testing for ammonia at the same time. Just like the ammonia, nitrite levels should rise steadily until they suddenly plummet.
6. Test for nitrates to see if the tank is ready. Once nitrite levels start dropping, it is time to start testing for nitrates. This is the last step in the process. You want to be able to detect nitrates in the water but not ammonia or nitrites. In other words, ammonia should test at 0 ppm, nitrites at 0 ppm, and nitrates above 1 ppm.
   • Nitrates are important for the survival of fish, but both ammonia and nitrites can kill fish. You should only be detecting nitrates when you put fish into the tank.
7. Add one or two fish at a time to avoid spiking ammonia levels. Once your tank has cycled successfully without fish, you can slowly start adding fish to your tank. Only add one or two at a time, or else the ammonia levels might rise too quickly. Wait a few weeks before adding the next two fish.
   • Remember to reduce the temperature before adding fish. It should be around {{safesubst:#invoke:convert|convert}}.
   • Ammonia is produced by fish waste. Your tank can naturally adjust the levels if one or two fish is added. If you start adding more all at once, they will produce too much waste that will pollute their water.

Cycling with Fish

1. Choose a hardy species that can produce ammonia for you. Certain species of fish can do the work of cycling for you by slowly and naturally increasing the ammonia in the tank. It is vital that you use the correct type of saltwater fish, however. These include:
   • Chromis
   • Clownfish
   • Basslet
   • Grouper
   • Lionfish
   • Hogfish
   • More aggressive species, such as damsels and triggerfish, can be used, but they must live in the tank alone or they will attack other fish.
2. Introduce only one or two fish. You only need one or two fish in your tank to cycle it. Do not add more. If too many fish are introduced before the tank is cycled, the fish will produce too much ammonia before it can be converted, and they will die off.
   • Do not increase the water temperature or add extra ammonia if you are cycling with fish or the fish may not survive. The fish will produce enough ammonia for you through their waste.
3. Test water levels daily to keep fish safe. Use your test kits to test the ammonia levels every day for two to six weeks. First ammonia will rise and suddenly drop, and then nitrite levels will do the same. When ammonia and nitrites are at 0ppm, you should notice rising nitrate levels. At this point, you can start adding more fish one or two at a time.
   • Do not add more fish if you can detect any ammonia or nitrites in the water.
4. Take action if ammonia is too high. If the ammonia level becomes too high, your fish might die. While some fish do have higher ammonia tolerance levels than others, it still a good idea to reduce the ammonia before they die off.
   • You can use a neutralizing agent, such as Amquel or Ammo-Lock, to protect your fish. This agent will still allow the cycling process to continue, but be aware that it may affect the accuracy of ammonia test kits.
   • Partial water changes might help reduce the ammonia. Once a week, change 25% of the water in the tank. Do this for three or four weeks.
   • Stop feeding the fish for a day or two. Rotting food can increase ammonia, and the fish are likely to stop eating if ammonia is present anyways. Stopping feeding for a short period may be able to allow levels to return to normal.

Ensuring the Success of the Cycle

1. Change the water every week to keep levels even. Once a week, you should replace 10% of the water in the tank. This will help balance out ammonia, pH, and salinity levels in the tank. Make sure that you mix the water with a salt mix before adding it to the tank.
2. Watch the salinity of the water to protect your fish. The salinity of the water tells you how much salt is in the water. Whether you are cycling with or without fish, you should make sure that the salinity remains between 1.025 and 1.027 (or 34-35 ppm).
   • The most common ways of measuring salinity are by adding a drop of tank water to a refractometer or hydrometer. These will then display a measurement.
   • If the salinity is too low, add more salt mix or seawater to the tank. If it is too high, try doing partial water changes.
3. Test the pH level of the tank. The pH of your water is also important to measure as you cycle. The ideal pH for a saltwater tank is between 8.0 and 8.4. If it is below 7.8 or above 8.5, you have a problem. Get pH testing kit to watch for any sudden changes.
   • Typically, if there is a problem with the pH of the tank, it is because the pH is too low. You can increase pH by using additives like limewater or by growing microalgae in the tank.
4. Keep the lights on to encourage bacteria growth. It is important to keep the aquarium lights running for between ten and twelve hours a day. Light encourages bacteria to grow, which will help speed up the cycling process.
5. Continue to test after the cycle is completed. Once your tank has been successfully cycled once, you should not have to do it again. Ammonia and nitrite levels should remain at 0 ppm. If you can detect any ammonia in your tank, your fish may not survive. You can correct ammonia levels by adding a neutralizing agent or by doing partial water changes.
   • Add only one or two fish at a time, even if you originally cycled with fish. Adding too many new fish to a tank can cause ammonia levels to rise too quickly.
   • You do not need to test everyday once the tank has been cycled. You might only test every two weeks.

Tips

• Crabs and mollusks can also be used to cycle the tank instead of fish, but because they do not produce as much waste, the process will take much longer.
• If the ammonia level rises suddenly in your tank, check the filter. A blocked filter can sometimes cause increases in ammonia.

Warnings

• Do not try to combine cycling with fish and cycling without fish. Increasing the temperature and adding extra ammonia will kill the fish. You must decide to either use fish to produce ammonia or add it yourself.
• While ammonia and nitrites are essential to starting the cycle, you should not be able to detect either once fish are added to the tank.
• Overfeeding your fish can cause ammonia to rise.

Sources and Citations

See also

• Start a Saltwater Reef Tank
• Start a Saltwater Aquarium
• Mix Saltwater for an Aquarium