| Scenario | Input | Converted | Notes |
|---|---|---|---|
| Pond test kit labeled “NO₂–N” | 0.50 mg/L (NO₂–N) | 1.64 mg/L (NO₂⁻) | Multiply by 46.0055/14.0067. |
| Seedling tray reservoir reading | 800 µg/L (NO₂⁻) | 0.800 mg/L (NO₂⁻) | µg/L ÷ 1000 = mg/L. |
| Lab report in mmol/L | 0.03 mmol/L (NO₂⁻) | 1.38 mg/L (NO₂⁻) | mmol/L × 46.0055 = mg/L. |
- NO₂–N to NO₂⁻: mg/L(NO₂⁻) = mg/L(NO₂–N) × (46.0055 / 14.0067)
- NO₂⁻ to NO₂–N: mg/L(NO₂–N) = mg/L(NO₂⁻) × (14.0067 / 46.0055)
- Molar units: mg/L(NO₂⁻) = mmol/L × 46.0055
- Micro-molar: mg/L(NO₂⁻) = µmol/L × 46.0055 ÷ 1000
- Mass estimate: mass(mg) = mg/L(NO₂⁻) × volume(L)
- Enter your nitrite reading exactly as reported.
- Select the unit shown on the kit or lab sheet.
- Choose the target unit required by your guideline.
- Optional: enable water volume to estimate total mass.
- Press Submit to display results above the form.
- Export CSV or PDF for logs and maintenance records.
Nitrite can stress fish and beneficial microbes, especially during new system cycling. Consistent units help you compare readings across time and tools.
If nitrite rises, review aeration, feeding, filtration, and water changes. Consider professional testing for persistent or severe spikes.
Why unit labels matter in garden water
Garden ponds, aquaponics beds, and storage tanks often get tested with different kits over time. Some kits display nitrite as NO₂⁻, while others display NO₂–N. Because the reporting basis changes, two readings can look different even when the water is unchanged. This calculator standardizes every entry to mg/L as NO₂⁻ first, then converts to your selected output so your records remain comparable.
Conversion factors used in the calculator
NO₂–N represents only the nitrogen mass inside the molecule, while NO₂⁻ represents the full nitrite ion mass. The calculator uses molecular masses of 46.0055 g/mol for NO₂⁻ and 14.0067 g/mol for N. The ratio 46.0055/14.0067 equals 3.2840. Multiply NO₂–N by 3.2840 to get NO₂⁻, or multiply NO₂⁻ by 0.3046 to get NO₂–N for guideline matching.
Molar reporting and lab-style results
Laboratories and some sensors report mmol/L or µmol/L. The tool converts molar units using 46.0055 g/mol, which becomes mg/L directly when multiplied. For instance, 0.03 mmol/L equals 1.380 mg/L as NO₂⁻, and 50 µmol/L equals 2.300 mg/L as NO₂⁻. This lets you compare lab reports, meters, and color charts without guessing. For quick visual checks.
Using volume to estimate total nitrite mass
Concentration indicates intensity, but not total load. When volume is enabled, the calculator estimates mass as mg/L × liters, reporting both mg and g as NO₂⁻. Total mass supports better decisions for partial water changes, topping up reservoirs, or evaluating whether a biofilter change actually reduced the system’s overall nitrite burden.
Operational checklist for safer trends
Log date, weather, temperature, pH, and system notes beside the converted value. Compare weekly averages, not single spikes. If readings rise, increase aeration, confirm pump flow, remove trapped debris, and reduce feeding or fertilizers temporarily. Retest after corrective steps, and keep the same unit in your dashboard so trend lines stay reliable.
FAQs
What is the difference between NO₂⁻ and NO₂–N?
NO₂⁻ is the full nitrite ion. NO₂–N reports only the nitrogen part of nitrite. The numbers differ by a fixed molecular-mass ratio, so you must convert before comparing limits or past logs.
Which unit should I store in my garden records?
Pick one standard unit for your dashboard and keep it consistent. Many pond and aquaponics guides use mg/L as NO₂–N, while many test kits show mg/L as NO₂⁻. This calculator lets you store either reliably.
Is ppm the same as mg/L here?
For dilute water, 1 ppm is treated as 1 mg/L, which is the common field practice. If your solution is highly saline or dense, laboratory methods may differ, so consider lab reporting units instead.
Why does the calculator offer mmol/L and µmol/L?
Some laboratories, probes, and scientific references report nitrite in molar concentration. Using molar units can simplify comparisons across ions and supports calculation workflows where molecular mass conversions are required.
How does the volume option help gardeners?
Volume converts concentration into total mass. Knowing total nitrite helps plan partial water changes, estimate removal needs, and evaluate whether filter improvements or management changes reduced the overall load in a pond or tank.
What should I do if nitrite stays high?
Increase aeration, confirm filtration flow, reduce organic inputs, and check for overfeeding or decaying matter. Retest after changes and track trends. If livestock are stressed or levels are severe, seek local water-quality guidance.