Aquarium Fertilizer Dosing Calculator
Created by: Ethan Brooks
Last updated:
Calculate optimal fertilizer doses for your planted aquarium using popular dosing methods like EI (Estimative Index), PPS-Pro, or lean dosing. Get weekly nutrient targets for nitrogen, phosphorus, potassium, and iron based on tank volume and plant density.
Aquarium Fertilizer Dosing Calculator
AquariumCalculate optimal fertilizer doses for planted aquariums using EI, PPS-Pro, or lean dosing methods
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What is an Aquarium Fertilizer Dosing Calculator?
An Aquarium Fertilizer Dosing Calculator determines the correct amount of liquid fertilizer to add to your planted tank based on tank volume, plant density, and dosing method. Proper fertilization ensures plants have all necessary nutrients for healthy growth without promoting algae.
This calculator supports popular dosing methods like EI (Estimative Index), PPS-Pro, and lean dosing, providing daily or weekly dosing schedules for macronutrients (NPK) and micronutrients.
Fertilizer Dosing Formulas
EI Dosing Targets (per week):
Nitrate (NO3): 20-30 ppm | Phosphate (PO4): 2-3 ppm | Potassium (K): 20-30 ppm | Iron (Fe): 0.5-1 ppm
PPS-Pro Targets (daily):
NO3: ~1.4 ppm/day | PO4: ~0.1 ppm/day | K: ~1.3 ppm/day
Dosing Method Comparison
EI (Estimative Index): Developed by Tom Barr, EI provides excess nutrients so plants are never limited. Weekly 50% water changes reset levels and prevent accumulation. Best for high-tech tanks with CO2 injection and strong lighting.
PPS-Pro (Perpetual Preservation System): A leaner approach that doses daily to maintain stable, moderate nutrient levels. Smaller weekly water changes (20-30%) are sufficient. Good balance between growth and algae control.
Lean Dosing: Minimal fertilization for low-tech tanks without CO2. Relies partly on fish waste for nitrogen and phosphorus, supplementing only potassium and micronutrients. Best for slow-growing, undemanding plants.
Frequently Asked Questions
How often should I fertilize my planted aquarium?
Most planted tanks benefit from daily or every-other-day dosing of liquid fertilizers. Root feeders need root tabs every 2-3 months. High-tech tanks with CO2 typically dose macros and micros on alternating days. Low-tech tanks may only need weekly dosing.
What is the EI (Estimative Index) dosing method?
EI dosing provides excess nutrients so plants are never limited, then weekly 50% water changes reset nutrient levels. It's simple and effective for high-tech tanks: dose macros (NPK) 3x/week, micros 3x/week on alternating days, with a weekly reset via water change.
What are macro and micro nutrients for aquarium plants?
Macronutrients (needed in larger amounts) are nitrogen (N), phosphorus (P), and potassium (K). Micronutrients (trace elements) include iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B). Plants need both categories for healthy growth.
Can I overdose aquarium fertilizers?
Most fertilizers are safe in reasonable excess, but copper-based micros can harm invertebrates at high levels. Iron overdose can promote algae. The EI method intentionally overdoses then resets weekly. Watch for algae as a sign of imbalance rather than excess nutrients alone.
Why are my plants showing nutrient deficiency?
Common deficiencies: Yellow older leaves = nitrogen deficiency. Yellow new leaves with green veins = iron deficiency. Holes in leaves = potassium deficiency. Stunted tips = calcium/magnesium deficiency. Ensure you're dosing a complete fertilizer or supplement specific nutrients.
Do I need fertilizer if I have fish in my planted tank?
Fish waste provides some nitrogen and phosphorus, but rarely enough potassium, iron, or other micronutrients. Most planted tanks need supplemental fertilization. Heavy fish loads may require less nitrogen dosing but still need other nutrients.
What's the difference between liquid fertilizers and root tabs?
Liquid fertilizers feed water-column feeders (stem plants, floating plants) and are dosed regularly. Root tabs feed heavy root feeders (swords, crypts, vallisneria) and are pushed into substrate every 2-3 months. Many tanks use both.
Should I dose fertilizer with CO2 or without?
High-tech tanks (with CO2) need more fertilizer because plants grow faster. Low-tech tanks (no CO2) need less - excessive nutrients without CO2 to drive growth can cause algae. Match your fertilizer dosing to your lighting and CO2 levels.
Sources and References
- Tom Barr, "Estimative Index Fertilization Method", Barr Report, 2024
- Planted Tank, "PPS-Pro Dosing Guide", Aquatic Plant Central, 2024