A 40-gallon (91 × 46 × 40 cm) low-tech Walstad tank: soil under a sand cap, no CO₂ injection, no filter to clean, 9 hours of light a day. Plants, animals and the bacteria in the substrate run the nitrogen cycle between them. There is nothing to win and nothing to lose. It is a place that keeps going.

click

Any animal or plant — its name, role, age and generation.

Feed

A pinch of food. Populations respond, nitrate rises, plants pull it back down.

Trim

Then click or drag across a plant. Cutting growth exports the nitrogen locked in it, and lets light reach what is growing underneath.

1–6

Time speed. At Real one second here is one second in the tank; the light follows your clock.

space

Pause. C cycle view, L log, H hide the interface.

drag

Anywhere on the glass to look around a little.

It keeps running while you are away and catches up when you come back. The state is stored in this browser only.