Instructions
Provide a deep sand bed at the base of the tank to reduce nitrogen levels naturally. According to online publication Aqua World Aquarium, the tank should have at least a 2-inch bed of fine sand for this to occur.
Changing water regularly will stem the accumulation of nitrated over time. 100-percent water changes may be required at least every month keep nitrate at a safe level.
Purchase nitrate-removal products such as a Nitrate Sponge. This product slowly absorbs nitrogen, gradually lowering nitrogen levels in the tank. These products can be purchased online or at fish tank specialist stores.
How to Lower the NO Levels of Your Fish Tank
Nitrogen (NO) levels in a fish tank must be monitored closely to ensure fish and plants are healthy. Generally, nitrogen is produced in a fish tank as a result of fish excretions being oxidized into nitrate. The recommended nitrogen levels in your fish tank depend on many factors, including the size of the tank and the species of fish and plants in the tank.