How many grams of dry salts to dose your planted tank to hit your target nitrate, phosphate, potassium and iron. Set targets yourself, or use a preset.
Use the actual water volume, not the tank's rated size. CSM+B is about 7% iron; change it if your trace mix differs.
EI is usually dosed three times a week (so roughly triple these figures over a week), with a big water change at week's end. Lean dosing is gentler, once or twice a week.
| Salt | Provides | Grams per dose |
|---|---|---|
| KNO₃ (potassium nitrate) | nitrate + some K | – |
| KH₂PO₄ (monopotassium phosphate) | phosphate + some K | – |
| K₂SO₄ (potassium sulphate) | tops up potassium | – |
| CSM+B / trace mix | iron + micros | – |
Estimative Index supplies nutrients in slight excess so plants are never limited, then resets levels with a big weekly water change. This calculator turns your targets into grams of dry salts.
Depends on target and volume. KNO₃ gives 613 ppm nitrate per g/L, KH₂PO₄ 698 ppm phosphate, K₂SO₄ 449 ppm potassium; the tool applies these to your figures.
A common high-tech EI dose is about 7.5 ppm nitrate, 1.3 ppm phosphate and 7.5 ppm potassium three times a week. Low-tech tanks dose leaner. Both presets are built in.
Ferts feed plants but do not replace good CO₂ and light: dial in gas with the CO2 calculator, keep an eye on nutrients that fuel algae, and start with beginner aquarium plants.
Estimates for dry-salt (EI-style) dosing, using standard nutrient fractions: KNO₃ gives 613 ppm NO₃ and 387 ppm K per g/L; KH₂PO₄ gives 698 ppm PO₄ and 287 ppm K per g/L; K₂SO₄ gives 449 ppm K per g/L. The K from your nitrate and phosphate salts is counted first, and K₂SO₄ only makes up the shortfall. Weigh with a 0.01 g jeweller's scale; teaspoon measures are only rough because salt density varies. Dosing feeds plants, it does not replace water changes or good CO₂ and light.