Methods for Cycling an Aquarium Faster

A new aquarium must go through the nitrogen cycle before it is safe to add fish, and typically, a tank takes six to eight weeks to complete the process. During this time, ammonia, nitrites and nitrates rise to toxic levels until healthy bacteria develop and colonize the filter, stabilizing the water chemistry. Reduce cycling time by introducing an established colony of good bacteria to kick-start the nitrification process and ensure healthy water chemistry within the first two weeks.

  1. Gravel from an Established Aquarium

    • Acquire 1 or 2 cups of old gravel from an established aquarium. Used gravel is often available free of charge from a local pet store's non-display tanks or you could ask a fellow fish-keeper for a handful of mature substrate to seed your tank. Transport the gravel in some of its original tank water to sustain the bacterial colony. Sprinkle the dirty gravel on top of your substrate and leave it to integrate biologically. The good bacteria will naturally migrate through the substrate and into the filter, reducing the nitrogen cycle to around two weeks.

    Media from a Mature Filter

    • The floss or media inside a tank filter harbors most of the healthy bacteria that your aquarium needs to maintain stable water chemistry. A new tank does not have a colonized filter, but used media from an established filter kick-starts the process, and instantly introduces good bacteria to your fish tank. Take the floss or sponge layer from a working, mature aquarium filter and place it in your new tank's filter box or cartridge. Alternatively, wrap the media in a piece of netting and position it on the substrate. The bacteria will populate the gravel and filter, cutting down cycling time to a week or two.

    Commercial Beneficial Bacteria Solution

    • A quick-fix for stable water chemistry is a commercial beneficial bacteria solution. There are several brands available, but they all produce the same end result from a bottle of live, good bacteria in a clear solution. Measure the volume of your aquarium and add the appropriate dose directly to the water. The live bacteria quickly colonize the gravel, filter and plants, stabilizing ammonia and controlling potential nitrite and nitrate problems. Follow the directions and add subsequent doses accordingly. A tank may complete the nitrogen cycle and become ammonia-free within two weeks when using a commercial beneficial bacteria solution.

    Tips for Success

    • Replace 10 to 15 percent of the water every two days to keep ammonia levels under control. Even if you complete the nitrogen cycle in a week or two, toxic chemicals may still develop when you add fish. Check the water for ammonia, nitrites and nitrates once a week with an aquarium test kit and change 50 percent of the water if results are at the high end of the test chart.