Decision essentials
Key points
Ammonia or nitrite changes the priority.
Colour guides but does not prove.
Clear water is not necessarily safe water.
Filter troubleshooting
Classify before intervening
Settling dust suggests particles; a pale haze after major disruption may accompany bacterial activity; uniform green points toward microalgae, while transparent amber often reflects tannins.
Check for new substrate, overfeeding, filter cleaning or a light increase.
Filter troubleshooting
Match the response to the evidence
If livestock struggle or nitrogen compounds are detectable, increase aeration and make appropriate water changes. For particles, capture them and stop their source.
Stacking clarifiers, bottled bacteria and deep cleaning hides cause and effect.
From evidence to action
Decision matrix
| Situation | What to do | Why |
|---|---|---|
| White haze after service | Test ammonia/nitrite | Rule out instability |
| Uniform green | Review light and nutrients | Likely microalgae |
| Settling particles | Fine-filter and remove source | Physical load |
Check the result
Record the symptom and time before intervening. Repeat the same check afterwards, watch breathing and behaviour, and keep a timeline; if the problem worsens, prioritise safety and reassess the diagnosis. For “Cloudy aquarium water: identify the cause before treating it”, use clear water is not necessarily safe water as the final article-specific check.
Evidence
Sources and scope
Sources include institutions, technical studies and manufacturers. Chezur separates established mechanisms from editorial decisions for home aquariums.