Aquarium Cycling Tracker
Track the nitrogen cycle and know when your tank is safe for fish.
How it works
The nitrogen cycle: Ammonia → Nitrite → Nitrate. A tank is cycled when it can process a dose of ammonia to 0 ppm ammonia and 0 ppm nitrite within 24 hours, with nitrate present. Fishless cycling typically takes 3-6 weeks.
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Formula & Method
The nitrogen cycle: Ammonia → Nitrite → Nitrate. A tank is cycled when it can process a dose of ammonia to 0 ppm ammonia and 0 ppm nitrite within 24 hours, with nitrate present. Fishless cycling typically takes 3-6 weeks.
Example Calculation
Day 0 dose ammonia to 2-4 ppm; ammonia falls and nitrite rises (~week 2); nitrite then falls and nitrate appears (~week 4). When both ammonia and nitrite read 0 in 24h, the tank is cycled.
Frequently Asked Questions
How long does it take to cycle a fish tank?
Four to six weeks for a fishless cycle at 24-26 C. Seeding the filter with mature media from an established tank is the most effective way to shorten it, sometimes to under two weeks.
How do I know when my tank is cycled?
When you can dose ammonia to 2-4 ppm and both ammonia and nitrite read zero within 24 hours, with nitrate present. A single clear test is not enough - repeat it for two consecutive days.
Why is my nitrite stuck at a high reading?
Most often pH has dropped below about 6.5, which halts the nitrite-oxidising bacteria. Test KH, do a partial water change to restore buffering, and the cycle usually resumes within days.
Can I cycle a tank with fish in it?
It is possible with hardy fish, very light stocking and daily water changes to keep ammonia and nitrite under 0.25 ppm, but it is stressful for the fish and slower. A fishless cycle is better in every respect.
Do bottled bacteria products work?
Results vary widely by brand and by how the product has been stored. Some meaningfully shorten the cycle; many do nothing. Mature filter media from an established tank is far more reliable.