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This tool applies a standard formula from the relevant domain. The computation is deterministic — given the same inputs, the result is always identical. The formula accounts for the primary variables that determine the output.
Weekly dose scaled from 50 gal baseline: NO₃ 20ppm, PO₄ 3ppm, K 30ppm per weekThe calculation requires: Tank Volume (gallons), KNO₃ Stock (g/L in 500ml), KH₂PO₄ Stock (g/L in 500ml), K₂SO₄ or K (g/L in 500ml). Each parameter contributes to the final result according to the formula above. Accuracy depends on the precision of your input measurements.
Updated: July 2026
A typical use case demonstrating the calculator with representative values.
→ Calculated result based on the formula and provided inputs
Enter your own values to get a personalized result for your specific situation.
→ Result calculated from your specific input values
Check the expected unit for each input field (shown as suffix). Converting between imperial and metric units before entering values prevents calculation errors.
When a formula combines multiple measurements, all inputs must use compatible units. Convert everything to the same system (metric or imperial) before calculating.
Calculate Estimative Index macro doses for your tank volume. Free ei fertilizer dosing calculator for planted aquariums, water chemistry, and reef tanks. It applies the calculation formula (Weekly dose scaled from 50 gal baseline: NO₃ 20ppm, PO₄ 3ppm, K 30ppm per week). For example: 40 gal tank, standard ei stock solutions — A typical use case demonstrating the calculator with representative values.