Tankline: Aquarium Calculator

Tankline is an aquarium calculator built around your tank's real water volume. Set up a tank profile once, and every calculator uses its net volume, so your dosing, salt and water change numbers start from the water actually in the tank rather than the glass size. Made for freshwater, planted, brackish, reef and pond keepers. It works fully offline, with no account and no ads. ━━━━━━━━━━━━━━━━━━━━ TANK VOLUME, DONE PROPERLY ━━━━━━━━━━━━━━━━━━━━ Gross tank size is not the volume you dose for. Tankline works out net water volume step by step: - 7 tank shapes: rectangle, cube, bow front, cylinder, half cylinder, hexagon and corner tanks - Labelled shape diagrams so you know exactly what to measure - Water level entry, for tanks not filled to the rim - Deductions for substrate (with adjustable porosity) and rock or hardscape - Sump or filter volume added on top - A clear breakdown from gross volume to net volume ━━━━━━━━━━━━━━━━━━━━ CALCULATORS ━━━━━━━━━━━━━━━━━━━━ - Fertilizer and treatment dosing: scale a label ratio such as "5 ml per 50 L" to your tank, dose to a target increase in mg/L, or check what a given dose adds. Includes partial doses and daily splits. - Water change calculator: see how nitrate or another parameter drops over several changes, find how many changes or what change size reaches your target, and estimate the level your weekly routine settles at. - Reef salt mix: grams of salt for new saltwater using your salt brand's own mix rate, plus salinity correction with fresh water or saltwater. - Salinity converter: ppt to specific gravity and back. - CO2 calculator: estimate CO2 from pH and KH, with a drop checker colour guide for planted tanks. - Water hardness converter: dGH, dKH, ppm and meq/L, plus temperature and volume units. Every calculator shows the formula it uses, and results can be saved to a tank or copied. ━━━━━━━━━━━━━━━━━━━━ WATER PARAMETER LOG ━━━━━━━━━━━━━━━━━━━━ - Record ammonia, nitrite, nitrate, phosphate, pH, KH, GH, temperature, salinity, calcium, magnesium and alkalinity - Add your own custom parameters and units - Charts for 7 days, 30 days, 90 days or all time - Set a target range per parameter, shown as a band on the chart ━━━━━━━━━━━━━━━━━━━━ MAINTENANCE TRACKER ━━━━━━━━━━━━━━━━━━━━ Set intervals for water changes, filter cleaning and other tasks. Each task shows as OK, due or overdue when you open the app, and one tap marks it done. ━━━━━━━━━━━━━━━━━━━━ YOUR DATA STAYS ON YOUR DEVICE ━━━━━━━━━━━━━━━━━━━━ - Works fully offline - No sign-up, no ads, no tracking - No device permissions required - Export and import a backup file whenever you choose ━━━━━━━━━━━━━━━━━━━━ DESIGNED FOR EVERYDAY USE ━━━━━━━━━━━━━━━━━━━━ - Litres, US gallons or imperial gallons; cm or inches; °C or °F - Light and dark themes, with dynamic colour on supported devices - Layouts for phones, tablets and foldables - Large text and screen reader support Tankline gives calculated estimates. Always follow product labels and confirm water parameters with your own test kit.