Nitrogen for plants (nitrate as a nutrient)
In planted freshwater aquariums, nitrates are not just a waste product but the main nitrogenous nutrient for plants. Too low a level limits growth.
Detailed explanation
In a planted aquarium the relationship with nitrates changes completely. In a planted aquarium they are an essential nutrient.
The nitrate target for a planted aquarium is 10-25 mg/l. Below 5 mg/l the plants show signs of deficiency: old leaves turning yellow.
The dosage is done with potassium nitrate (KNO3). The nitrate/phosphate ratio (Redfield ratio) should be approximately 10:1.
In Tom Barr's EI (Estimative Index) method nitrates are dosed at 20-30 mg/l with a large weekly water change (50%) to reset everything.
In aquariums with few plants the problem is excess nitrates. In densely planted aquariums the opposite problem is common: the plants consume all the nitrates.
Reference values by aquarium type
| Aquarium type | Recommended range |
|---|---|
| Tropical freshwater | 10 - 25 mg/lFor densely planted aquariums |
How it is measured
Drop test for nitrates (API, Salifert, JBL).
What happens when it is too low
Nitrogen deficiency. Yellow old leaves. Slow growth.
What happens when it is too high
Nutrient imbalance. Possible algal bloom.
Coralia Lab monitors this parameter with AI diagnostics. Tank Score alerts you when a value moves outside the recommended range for your aquarium.
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