How to Cycle a Tank Properly Cycling your tank means building up bacteria to handle fish waste. It usually takes 30 to 45 days for a healthy balance to form. Adding too much ammonia early on can cause high nitrite levels and slow everything down. Keep both ammonia and nitrite under 2 ppm, and your tank will be ready sooner. Follow for more expert tips on how to properly cycle your aquarium in as little as 9 days. #AquariumCycling #NitrogenCycle #AquariumBacteria | DrTims Aquatics