Two weeks since setup, and the cycle is entering its next phase. Nitrite is rising—which is exactly what should happen, even if it makes us a little nervous with snails in the tank.
Test Results
| Parameter | Result | Trend |
|---|---|---|
| Ammonia | 0.25 ppm | Stable |
| Nitrite | 0.5-1.0 ppm | UP from 0.25 |
| Nitrate | 0 ppm | Same |
What’s Happening
The rise in nitrite is a classic sign that we’re entering “Phase 2” of the nitrogen cycle.
Phase 1 (now established): Ammonia-oxidizing bacteria (AOB) convert ammonia to nitrite
Phase 2 (now beginning): Nitrite-oxidizing bacteria (NOB) convert nitrite to nitrate
The NOB population lags behind the AOB population. They’re slower to establish. This means nitrite builds up faster than it gets converted—temporarily.
Think of it like a factory with two assembly lines. The first line (AOB) is running full speed, producing nitrite. The second line (NOB) is still ramping up. Until it catches up, nitrite accumulates.
Day 14 - Plants growing, cycle progressing
Snail Check
Our three Nerites are handling the nitrite rise well so far:
- All three actively grazing
- No surface clustering
- Clean trails visible on the glass
- One found a favorite spot on the coral
At 0.5-1.0 ppm nitrite, they’re in their tolerance zone. We’ll start worrying if it exceeds 2 ppm.
The Next Few Days
Based on typical cycling patterns, we expect:
- Nitrite to continue rising (possibly to 2-5 ppm)
- This is the “nitrite spike” phase
- Could last 3-10 days
- Then nitrite should start dropping as NOB catch up
We’re prepared to do water changes if nitrite gets dangerously high and stresses the snails. Otherwise, we’ll let the biology do its work.
Status: Entering nitrite phase - NOB bacteria establishing