How Plants Remove Nitrate
Plants absorb nitrate as nitrogen for protein synthesis. Fast-growing plants absorb more than slow-growing ones.
Floaters with access to atmospheric CO2 grow fastest, removing nitrate at 2-3x the rate of submerged plants.
Best Plants for Nitrate Removal
Floaters: Amazon frogbit, water lettuce, duckweed (last resort — invasive).
Stems: Hygrophila polysperma, Limnophila aromatica, Hornwort, Anacharis.
Crypts: slow but consistent absorbers; less aggressive but reliable.
- ✦Trim stems regularly — floaters and stems must keep growing to absorb nitrate
- ✦Add liquid fertilizer to ensure phosphate, potassium, micros do not become limiting
- ✦Remove and discard trimmings — they re-leach nitrate as they decompose
Heavy Stocking + Heavy Planting Balance
A heavily planted tank can support 30-40% more fish before nitrate becomes a problem.
Test weekly to verify your setup — every tank is different.
Limitations
Plants do not remove old water buildup of dissolved organics, hormones, or trace minerals. Water changes are still needed monthly.
In a fully cycled, heavily planted tank, monthly 25% water changes can replace weekly water changes.