Calculators
Each calculator shows its formula and the constants behind it, so you can check the number instead of trusting it. They run in your browser; nothing you type is sent anywhere.
The dosing tools work from molar masses computed with IUPAC atomic weights, so "1 g of potassium nitrate in 100 L" becomes an exact figure for nitrate and potassium rather than a rule of thumb. The EI and PPS-Pro planner keeps each method's published numbers apart from the arithmetic it adds. The CO2 calculator uses the carbonate equilibrium with a temperature-corrected constant and shows the common chart shortcut next to it, along with the conditions under which both are wrong.
Fertilizer dosing
- Dry fertilizer dosingConvert grams of KNO3, KH2PO4, K2SO4, Epsom salt or a trace mix into mg/L for your tank, or work back from a target ppm. Every molar mass is shown.
- EI and PPS-Pro plannerTurn the Estimative Index and PPS-Pro, as their authors published them, into grams or milliliters for your tank, with the build-up each schedule produces.
- Water-change dilutionWhat a water change does to nitrate, phosphate, TDS or any dissolved level, the change needed to hit a target, and where weekly dosing settles.
- Stock solutionPlan a bottle of dissolved fertilizer salts: what each milliliter adds to your tank, how long the bottle lasts, and whether the salts will dissolve.
Water chemistry
- CO2 from KH and pHEstimate dissolved CO2 in mg/L from carbonate hardness and pH, with a temperature-corrected constant, the usual chart shortcut, and the pH needed for a target.
- Hardness converterConvert GH and KH between German degrees, mg/L as CaCO3, mmol/L, meq/L, grains per gallon and French or English degrees, with each definition shown.
Tank and substrate
- Tank volume and weightNet water volume and weight for rectangular, cylindrical, bow-front, corner and hexagonal aquariums, minus glass, the gap below the rim and the substrate.
- Substrate volumeHow many liters of aqua soil, sand or gravel a tank needs for a flat bed or a front-to-back slope, and how many bags that is.