Tools and calculators
Calculators that show their working. A result with a hidden formula asks to be trusted rather than checked, and aquarium arithmetic is easy enough to check.
The standard these follow
Inputs visible, formula visible, units defined, conversions shown, assumptions stated, intermediate values displayed, limitations listed. A tool that cannot meet all seven is not published, which is why the second list below exists.
Available now (10)
Every one shows its formula, its assumptions, its intermediate values and its limitations. Nothing is behind a paywall.
- Aquarium volume calculatorWork out how much water a tank actually holds, from its dimensions — including the substrate and freeboard that the label ignores.tank
- Water change calculatorSee what a water change of a given size actually does to a measured parameter — and how many changes it takes to reach a target.water
- Temperature converterCelsius, Fahrenheit and Kelvin, with the aquarium-relevant ranges marked.conversion
- Hardness and alkalinity converterConvert between German degrees, ppm as calcium carbonate and milliequivalents per litre — for both GH and KH.conversion
- Filter turnover calculatorTurn a filter's rated flow into real turnover, allowing for the media and head loss the rating ignores.equipment
- Free ammonia calculatorA test kit reports total ammonia. This works out how much of it is the toxic un-ionised form, from your pH and temperature.water
- Heater sizing calculatorEstimate the heater wattage needed to hold a target temperature above the coldest room temperature the tank will see.equipment
- Substrate calculatorHow much sand, gravel or soil a given tank footprint and depth needs, by volume and by mass.tank
- CO₂ estimatorEstimate dissolved CO₂ from pH and KH — and see exactly when the estimate stops being trustworthy.water
- Compatibility checkerAssess any two organisms in the catalogue against each other, with the reasoning, the concerns and the conditions shown.compatibility
Specified but not yet published (6)
Registered, designed and deliberately withheld. Each says what it is blocked on — publishing a calculation we cannot defend would be worse than not having it.
- Stocking adviserAssess a proposed stocking plan against welfare constraints — adult size, footprint, group requirements, territory and relative bioload. Blocked on: The constraint engine exists and is tested, but the relative bioload index needs validation against a wider range of real tanks before it is published as a number a keeper might act on. It will never return a capacity figure.not published
- Aquarium electricity cost calculatorEstimate the running cost of heating, lighting and filtration. Blocked on: Needs a defensible duty-cycle model for heaters. A heater's wattage is its maximum draw, not its average, and publishing wattage × hours would overstate cost by a factor of three or more.not published
- Salinity converterConvert between specific gravity, parts per thousand and conductivity for brackish and marine water. Blocked on: Specific gravity is meaningless without a reference temperature, and the conversion needs the full equation of state rather than a lookup. Deferred to the brackish domain pack.not published
- Cycling trackerRecord ammonia, nitrite and nitrate through a fishless cycle and see whether it is progressing. Blocked on: Requires persistent state, which AquariumHQ does not yet have. A stateless version would be a chart with no data in it.not published
- Water parameter interpreterEnter a full set of test results and get an interpretation that accounts for the interactions between them. Blocked on: The parameter band data exists on each water concept record. What is missing is the cross-parameter reasoning — ammonia interpreted against pH and temperature, nitrate against water change history — without which it would be six independent verdicts rather than one interpretation.not published
- Fertiliser dosing calculatorWork out dry salt doses for a target nutrient concentration in a planted tank. Blocked on: The arithmetic is straightforward; the responsible presentation is not. Dosing targets vary by methodology and publishing one set of numbers as authoritative would misrepresent an unsettled area.not published