Nitrogen cycle timeline

Drop an ammonia source into a virtual tank and watch NH₄ → NO₂ → NO₃ play out over the weeks of cycling. The chart you wish your first tank came with.

Stormy · the simulator

Two bacterial populations growing on a moving target. Stormy runs the same two-stage Monod kinetics the literature uses to model new-tank cycling — sliders for tank size and ammonia dose let you see how the curves shift.

Tank volume (L)Net water volume after substrate, decor, and hardscape — the volume that actually holds water.Daily ammonia dose (mg)Total mg of NH₄-N added per day. A fishless cycle dosed to 4 ppm in 60 L works out to ~250 mg/day for the first week.Days to simulateMost freshwater cycles complete in 4–6 weeks under default conditions.

How the simulation works

Two bacteria populations, two-stage Monod kinetics. Stage one converts NH₄ to NO₂ on a growth rate set by ammonia availability; stage two converts NO₂ to NO₃, lagging stage one by about a week as its substrate (NO₂) builds up.

Defaults match the literature for warm-water freshwater cycling at typical bioloads. Real tanks deviate based on temperature, pH, surface area for bacterial colonisation, and starting bacterial inoculum (a piece of mature filter media compresses the timeline by half).

In the app, Manfred logs your real NH₄, NO₂, NO₃ tests and overlays them on this kind of curve so you know exactly where in the cycle your tank actually is.

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