Dosing Calculator - Tools & Calculators
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Dosing Calculator
Calculate the amount of solution needed to reach a target nutrient level.
How much fertilizer do I need to add to my planted tank?
Why is proper fertilizer dosing important?
Aquatic plants require a balanced supply of macro and micronutrients for healthy growth. Underdosing leads to deficiency symptoms like yellowing leaves, stunted growth, and algae problems. Overdosing wastes money and can trigger algae blooms or harm sensitive livestock. Precise dosing ensures optimal plant health while keeping your tank balanced.
Key nutrients for planted aquariums
- Nitrogen (N): Essential for leaf growth – target 10–25 ppm NO₃ for high-tech tanks
- Phosphorus (P): Drives energy transfer and flowering – target 1–2 ppm PO₄
- Potassium (K): Regulates plant functions – target 10–30 ppm K
- Iron (Fe): Critical for chlorophyll – target 0.1–0.5 ppm Fe
- Micronutrients: Mg, Mn, Zn, B, Cu, Mo – usually included in comprehensive fertilizers
The dosing formula
Dose (mL) = (Target ppm − Current ppm) × Tank volume (L) ÷ Solution strength (mg/mL)
Example: To raise NO₃ from 5 to 15 ppm in a 100 L tank using a 1000 mg/mL solution: (15 − 5) × 100 ÷ 1000 = 1 mL
Common dosing methods
- Estimative Index (EI): Dose excess nutrients, reset with 50%% weekly water change – best for high-light, CO₂-injected tanks
- Perpetual Preservation System (PPS-Pro): Daily lean dosing based on plant uptake – suited for moderate setups
- All-in-One liquids: Pre-mixed solutions – convenient but less customizable
Target nutrient levels
| Nutrient | Low-tech tank | High-tech tank |
|---|---|---|
| NO₃ | 5–10 ppm | 10–25 ppm |
| PO₄ | 0.5–1 ppm | 1–2 ppm |
| K | 5–10 ppm | 10–30 ppm |
| Fe | 0.05–0.1 ppm | 0.1–0.5 ppm |
Dosing tips for success
- Test your water regularly – at least weekly for new setups, monthly for established tanks
- Dose consistently – same time each day helps maintain stable levels
- Adjust based on plant response – healthy growth means your dosing is on track
- Factor in water changes – they dilute nutrients, so dose after water changes