A set of practical, no-nonsense tools for the freshwater tank. Each is a guide to help you plan, not a lab measurement.
Litres and gallons from your dimensions, for rectangle, cube, cylinder, hexagon, bowfront and corner tanks.
How heavily stocked you are, on metabolic fish weight and filtration (the aquariumscience.org approach), plus group, tank-size, temperament and hardness checks.
A simpler how-many-fish check: enter your volume and your fish by adult length, get a stocking percentage from combined body length and a surface-area factor.
A sensible heater size from your volume and how far above room temperature you need to hold it.
How much sand, gravel or aquasoil to buy, in litres and kilograms.
Dissolved CO2 from your pH and KH, with a safe-range guide and a rough lighting estimate.
Grams of dry salts to hit your target nitrate, phosphate, potassium and iron, with EI and lean presets.
Gypsum, Epsom salt and baking soda to build RO or soft water up to a target GH and KH.
How much RO, rain or distilled water to blend with hard tap to hit a softer target hardness, as a ratio and litres of each.
How big a change to bring nitrate (or TDS) from its current level down to a target.
How much household ammonia to add to hit your target level for a fishless cycle.
What the heater, filter and light cost to run, per day, month and year.
The calculators give you numbers; these posts explain what to do with them.