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Mineral Chemistry
Phosphate
A limiting nutrient in reef tanks (target 0.02-0.1 ppm) but a required fertiliser in planted tanks (0.5-2 ppm) - context-dependent essential.
Unit: ppm Code: PHOS
📖 Overview
Phosphate is the most misunderstood aquarium parameter. In reef tanks it must be kept extremely low (0.02-0.1 ppm) - excess phosphate inhibits coral calcification and fuels algae. In planted freshwater tanks it must be dosed to 1-2 ppm - too little starves plants. Understanding your tank type determines whether phosphate is enemy or nutrient.
❓ Why It Matters
Reef: inhibits coral calcification above 0.1 ppm. Fuels algae blooms. Planted: essential plant macronutrient. Freshwater fish tanks: excess promotes algae, low levels are harmless.
🧪 Testing Methods
Hanna Instruments Ultra Low Range Phosphate Checker (reef standard). Salifert Phosphate. API Phosphate (freshwater, less precise).
📈 How to Raise
Potassium phosphate (KH2PO4) in planted tanks. Overfeeding (undesirable). Bone meal (planted tanks).
📉 How to Lower
GFO (granular ferric oxide) reactor. Lanthanum chloride dosing. Refugium with macroalgae. Manual export via cleaning and water changes.