Aquarium Fertilizer Dosing Calculator

Fertilizer Addition shows what your dosing adds per interval (based on dose + tank volume). Total includes your tap water values, so it reflects the nutrient level you’re actually starting from.

Because a water change dilutes nutrients. The calculator applies your water change percentage and then blends in your tap water nutrients (if entered), which is why values can drop or stabilize depending on your tap water.

As a general planted-tank guideline, many setups do well around NO₃ 10–25 mg/l, PO₄ 0.5–2.0 mg/l, K 10–30 mg/l, and Fe 0.05–0.2 mg/l. The best range depends on plant mass, light, CO₂, and water change routine.

Dashed lines indicate the value comes from tap water only (no fertilizer addition for that nutrient). This helps you see whether your baseline water already contains meaningful amounts.

Not automatically. Ratios are a rough indicator, but what matters is whether plants show healthy growth and algae stays controlled. Extremely high or low ratios can signal an imbalance, especially if one nutrient is near zero.

NH₄ and urea can be powerful nitrogen sources, but they’re best used in stable, matured tanks. If a system isn’t well-cycled or dosing is aggressive, these forms can increase algae risk. If you see algae, reduce NH₄/urea first.