mg/L
Ammonia
What is it
Ammonia is the first nitrogen waste released by fish, uneaten food and decomposing organics. Test kits often report total ammonia, which includes safer ammonium (NH4+) and toxic free ammonia (NH3).
Why it matters
Free ammonia damages gills and nerves quickly. Its toxicity rises with higher pH and temperature, so the same test value can be far more dangerous in alkaline warm water.
Interactions with other parameters
High pH and heat increase the toxic NH3 fraction. Chloramine-treated tap water and dead organics can also add ammonia unexpectedly.
Ideal ranges
| Tank type | Min | Max | Unit |
|---|---|---|---|
| Tropical community | 0 | 0 | mg/L |
| Planted high-tech | 0 | 0 | mg/L |
| Planted low-tech | 0 | 0 | mg/L |
| Shrimp tank | 0 | 0 | mg/L |
Out of range: what happens
Any ammonia in a stocked tank is a warning. Fish may gasp, clamp fins, show red gills or die suddenly, and the biofilter may not yet be mature enough for the waste load.
Common Myths
- •Ammonia is only a cycling problem; filter damage or overstocking can bring it back anytime.
- •Detoxifier replaces water changes; it only reduces risk while the system catches up.
How to measure
Use a liquid ammonia test and interpret the result with pH and temperature. During cycling or after filter trouble, test daily until readings return to zero.
How to adjust
Do immediate water changes, stop feeding briefly, add aeration and protect filter media. Detoxifiers can buy time, but the lasting fix is a working biofilter and lower waste input.
Pro Tips
After a power outage, check ammonia because oxygen-starved filter bacteria may have suffered.
Quarantine tanks need seeded media or very light feeding to avoid ammonia spikes.
