Instructions
Fishless Cycling
Set up the aquarium and fill it with water. Use some gravel, rocks, or ornaments from an active established tank if one is available. Include a heater and thermometer in the aquarium. Maintain a water temperature of 80 degrees Fahrenheit.
Use a filter with a biological filtration mechanism such as a sponge filter or a bio-ball cartridge. Set up the filter so that the outflow water splashes and agitates the surface to aerate the tank. Use additional aeration devices in larger aquariums, such as those 55 gallons or greater.
Introduce fish food into the uninhabited tank and allow it to decay -- the amount of fish food will depend on the size of the tank. Use a pinch of food for smaller tanks and sprinkle the water surface for larger tanks. Repeat this process daily.
Use a water testing kit to measure the nitrite levels of the aquarium. The decay of fish food will cause the nitrite and ammonia levels to spike, promoting the growth of beneficial bacteria. Test the water every 2 to 3 days.
Stop adding fish food to the aquarium once the ammonia and nitrite levels are no longer detectable by the testing kit. At this point, the aquarium has fully cycled and you can introduce fish to the tank.
Maintaining Water Quality
Avoid overcrowding the aquarium. Small fish require a minimum of 1 gallon of water for every inch of fish, and larger fish require at least 3 gallons of water for every inch of fish.
Feed the fish only what they can consume in 5 minutes; decaying food will quickly increase nitrite levels. Use a fish net or skimmer to remove any excess food after this time. Check the hiding places of fish or scavengers, such as crayfish, for hoarded food and remove it.
Introduce live plants to the aquarium to increase the water quality. Plants metabolize the harmful nitrates produced by nitrite-consuming bacteria and provide additional surface area for bacteria to grow on.
Remove any dead fish or plants from the aquarium as soon as you notice them; their decay will rapidly increase nitrite levels in the water.
Water Changes
Use tap water to fill buckets with the equivalent of 20 to 30 percent of the aquarium's water volume 1 or 2 days prior to a water change. This allows trapped chlorine in the tap water to dissipate naturally.
Remove 20 to 30 percent of the aquarium water and dispose of it. Use a siphon tube to vacuum any gravel and sand in the aquarium. Remove ornaments or rocks with heavy algae growth and soak them in a mixture of 1 tbsp. of plain bleach and one gallon of water. Rinse them thoroughly until no bleach odor is present before reintroducing them to the tank.
Replace the removed water with the dechlorinated water from Step 1.
Conduct water changes every 2 weeks. Test the water regularly for nitrite levels and adjust your changing schedule accordingly. Increase the frequency of the changes or the amount of water changed in response to detectable nitrite levels. Decrease feeding or skip a day or two if excessive nitrite levels persist.
How to Naturally Lower Nitrite Levels in a Freshwater Aquarium
A common killer in aquariums is excessive nitrite levels. Nitrite is a byproduct of fish excretion and is produced by the decay of organisms or food. High nitrite levels are toxic to fish and can easily wipe out a newly established aquarium. Keeping nitrate levels under control requires promoting the growth of beneficial bacteria to break down ammonia and nitrite into less harmful substances. Regular water changes can also reduce the proportion of nitrite in the water.