Foamy or bubbly surface
This looks like: organic film and protein froth — often feeding, dead critters, or lazy surface exchange
Why this happens
Protein skimmer vibes without the skimmer — organics churn at the surface when agitation meets waste. Small dead snails do it quietly.
How sure are we? High when feeding is rich and flow is lazy.
What to do right now
- Increase gentle surface ripple with filter or air.
- Remove duckweed mats trapping foam temporarily.
- Search for dead snails or shrimp; remove.
- Skim with paper towel once safely — then fix root feeding.
- Retest ammonia because decaying protein raises it too.
What not to do
- Don’t dose “foam reducer” potions before removing waste sources.
If that doesn’t fix it
Persistent foam + sick fish → bacterial infections look again.
Catch this earlier next time — log your water parameters in App-aquatic. Free forever.