The Nitrogen Cycle

Welcome to the Aquarium Simulator. Your goal is to maintain a healthy aquatic ecosystem by understanding and managing the nitrogen cycle. Tap "Introduction" in the header to revisit this at any time.

Ammonia (NH₃)

Fish continuously produce ammonia through their waste and respiration. Even small amounts are harmful to fish, and high concentrations can be lethal. Ammonia is the first stage of the nitrogen cycle.

Nitrite (NO₂⁻)

Beneficial bacteria called Nitrosomonas convert ammonia into nitrite. Nitrite is still toxic to fish, though less immediately dangerous than ammonia. It represents the intermediate stage of the cycle.

Nitrate (NO₃⁻)

A second group of bacteria called Nitrobacter convert nitrite into nitrate. Nitrate is far less harmful at moderate levels, but it accumulates over time and must be controlled through water changes and live plants.

A Balanced Tank

A healthy, fully cycled aquarium maintains near-zero ammonia and nitrite at all times. Live plants absorb nitrates as nutrients, and regular partial water changes prevent dangerous buildup.

Simulator Controls

Use the panel on the left to manage your tank. Your goal is to keep ammonia and nitrite as close to zero as possible at all times.

Fish

Guppy Guppies are small, low-waste fish that add about 0.5 ppm of ammonia per day.

Goldfish Goldfish are larger and produce significantly more waste, adding about 1.25 ppm per day.

Plants

Anubias A hardy, slow-growing plant that absorbs approximately 0.1 ppm of nitrate per day.

Hornwort A fast-growing plant that removes about 0.2 ppm of nitrate daily and grows visibly larger as nitrates are available.

Maintenance

Feed Fish Drops food into the tank. Any uneaten food decays and raises ammonia, so feed in moderation.

50% Water Change Immediately cuts the concentration of all nitrogen compounds in half, providing fast relief in a crisis.

Bacteria Boosters

Nitrifying Accelerates the conversion of ammonia into nitrite and then into nitrate, speeding up the cycling process.

Ammonifying Increases the rate at which organic matter breaks down into ammonia.

Denitrifying Converts nitrate directly into harmless nitrogen gas, removing it from the water entirely.

PEEBEDU

Aquarium Simulator

Introduction

Actions

Bacteria Boosters

Nitrifying Bacteria: Speeds up NH₃→NO₂→NO₃ conversion.

Ammonifying Bacteria: Breaks down waste faster, producing NH₃.

Denitrifying Bacteria: Converts NO₃ into harmless N₂ gas.

Add Fish

Guppy: Small fish, low waste output.

Goldfish: Large fish, high waste output.

Add Plants

Anubias: Hardy plant, slow nitrate absorption.

Hornwort: Fast grower, fast nitrate absorption.

Remove

— Danger Zone —

Removes all organisms and resets the nitrogen cycle and boosters.

Nitrogen Cycle Monitor

NH₃

0.00 ppm

NO₂⁻

0.00 ppm

NO₃⁻

0.00 ppm

Aquarium is new and clean!