Dosage: Add 8g Tetra NitrateMinus Pearls to 10 l of aquarium water (or use a top-filled lid for 15 litres of water). Distribute Tetra NitrateMinus Pearls evenly over the soil and as far as possible into the gravel. Re-dose every 12 months. If nitrate levels increase during the 12 month period, re-dosing is recommended.