Well, we knew it was coming. Nitrite hit 5.0 ppm today—the maximum our test kit can measure. Our snails are stressed, and we did our first water change.

Test Results

Parameter Result Notes
Ammonia 0.25 ppm Stable (good news)
Nitrite 5.0 ppm PEAKED
Nitrate 5 ppm First detection!
GH 3 dGH Soft water
KH 5 dKH Good buffering

First Nitrate Detected!

Buried in the scary nitrite number is actually great news: we detected nitrate for the first time. This proves the second-stage bacteria (NOB) are working. They’re converting nitrite to nitrate—the final, less toxic form.

The cycle is progressing. We just need to survive this nitrite spike.

Snail Stress Signs

With nitrite at 5.0 ppm, our Nerites showed clear stress:

  • Two of three climbed to the surface
  • Reduced grazing activity
  • One partially burrowed into the substrate

This is their way of seeking better oxygen and lower nitrite levels near the surface. Time to help them out.

Tank on Day 16

Day 16 - Nitrite peak, but we’re progressing

First Water Change

We did a 25% water change (about 5 gallons):

  1. Removed ~5 gallons with a siphon
  2. Added dechlorinated tap water slowly
  3. Temperature matched to avoid shock

The water change should dilute the nitrite from 5.0 ppm to roughly 3.75 ppm. Not perfect, but it gives the snails some relief while bacteria continue establishing.

Biofilm Skimming

While doing the water change, we noticed heavy biofilm on the surface. This can reduce gas exchange, lowering oxygen levels—bad when snails are already stressed.

We used a paper towel to skim the surface, removing the oily film. The surface looks cleaner and should allow better oxygen exchange now.

Water Hardness Results

We tested GH and KH for the first time:

  • GH: 3 dGH - Soft water! Perfect for our planned Cardinals and Chilis
  • KH: 5 dKH - Good buffering capacity, pH should stay stable

The soft water is interesting. Our coral hardscape hasn’t raised hardness much yet. We’ll monitor this over time.

Lessons Learned

  1. The nitrite spike is real and can be severe
  2. Snails are hardy but show stress at high nitrite
  3. Water changes are appropriate during cycling when livestock is present
  4. Surface skimming helps with oxygen levels

Status: NITRITE PEAK - First nitrate detected - First water change completed