Presets

A preset is a tank configuration paired with an optional seed, so loading one opens on a tank that is already somewhere in its life rather than on hour zero of an empty box. Five ship with the engine, and planted is the default.

The five tanks

Preset	The tank it represents	What it demonstrates
Bare Tank	40 L with nothing in it: no heater, no filter, no light, no substrate, bare glass	The uncycled floor. No colony, no bed to rot, and no surface beyond the glass — so the tank drifts to room temperature and stays chemically inert until something is added to it
Betta Cube	20 L nano, sponge filter, gravel, mesh lid, a low fixture on an 8 h day, heated to 26 °C in a 22 °C room off 18 °C tap	A small heated tank against a cold room. Low volume is the point: the same milligram reads several times higher here, and a water change swings the temperature the heater then has to pay back
Planted Tank	40 L, canister, aqua soil, no lid, no heater, a bright fixture on a 12 h day, CO₂ injected on a 10 h schedule at the 20–⁠30 mg/L a drop checker reads green, auto top-off on	The high-tech planted case, and an unheated one. CO₂ on a schedule swings pH across the day; an open top evaporates and the ATO answers it
Balanced Community	150 L, canister, aqua soil, heated to 27 °C, moderate light on a 10 h day, seven hardscape items	A large, well-equipped tank at rest. Volume and biofilter surface both scale up, so the same husbandry mistake reads far smaller here than in the cube
Big Angelfish Tank	300 L, canister, sand, heated to 26 °C on 200 W, moderate light on a 12 h day	Scale, on a lean bed. Sand carries a third of aqua soil’s colony surface and a fraction of its organic reserve, and the 200 W heater is the same element the 150 L community runs

What a preset carries

Half	Contents
Configuration	Capacity, room and tap water conditions, and every device the tank is built with — heater, filter, powerhead, lid, substrate, hardscape, light, CO₂, ATO, doser
Seed	The state it opens at. Four of the five seed 'cycled'; the bare tank seeds nothing

No shipped preset stocks fish or plants. The tanks are hardware and water; the livestock is the consumer’s to add.

What 'cycled' means

'cycled' is a claim about a tank that has been running a month, not only about its biofilter. It resolves against the tank at the moment the seed is applied, so a preset resized or rebuilt at the door still gets a colony, a bed and readings that fit it. Hardscape starts as bought.

Stock	Seeded to
AOB and NOB	The colony the seeded fish and the bed sustain at rest, never less than a month-old fishless colony’s share of the surface ceiling — so a preset, which stocks nothing, opens on that share
Substrate organic reserve	The share of a fresh bed’s mulm still unrotted on day 30
Substrate KH reserve	The share of a fresh soil bed’s buffer left on day 30
KH	The tap’s, or a fraction of it over aqua soil, less an equivalent per mole of the nitrate the bed’s rotted organics left
GH	The tap’s, less whatever KH the soil took — the bed takes both alike, and no more than the tap’s GH
Nitrate, phosphate, potassium, iron	What a month of the bed’s rot and leak leaves behind, discounted for the water changes a keeper would have done

A tank seeded this way is handed the outcome, not a shortcut through the mechanism: the tick loop takes it from there, and nothing catches up afterward.