01 · AquaGrow
What it is
A bloom is a population of tiny algae in the water. When much of it dies, decomposing material can use up oxygen. A sudden colour change needs testing; it is not a reason to add a chemical immediately.
Signs to watch for
- Water suddenly becomes clearer, brownish or different from its usual colour.
- Dead algal material or scum appears.
- DO falls, feeding drops or shrimp crowd the edges.
Common causes
- An unstable dense bloom changes after weather or light conditions change.
- Algae die after an unsuitable input or abrupt water-quality change.
- High nutrient and organic loads make the pond harder to manage.
How to confirm the cause
- Compare DO readings, morning and afternoon pH, and water appearance with recent records.
- Check transparency and ask for a microscope assessment if the bloom identity or condition is uncertain.
What to do immediately
- 1
Increase safe aeration and measure DO; treat surface crowding or low DO as an emergency.
- 2
Pause feed if shrimp are distressed. Stop fertiliser and unplanned pond inputs.
- 3
Ask a technician to assess the bloom and water tests before any correction. Do not apply an algaecide to a crashing bloom.
- 4
Monitor through the night and before sunrise. Use only a tested, controlled water-management plan.
Prevention: your practical checklist
- Track colour, transparency, DO and daily pH pattern rather than colour alone.
- Avoid overfeeding and sudden attempts to force a bloom.
- Prepare extra aeration for cloudy periods and high crop biomass.
When to call an expert
- Call urgently for a rapid colour change with weak shrimp, falling DO or deaths.
- Get help if the bloom repeatedly crashes or pH swings continue.
Farmer questions
Is a darker green pond always better?
No. A dense bloom can increase night-time oxygen demand. Use water readings and crop observations, not colour alone.
Should I kill the remaining algae?
Do not use an algaecide as an untested response. More dying algae may add to oxygen demand. Restore oxygen and get the cause assessed.
When should I check again?
Recheck during the event and through the night, especially before sunrise. A good afternoon reading does not rule out a night-time oxygen problem.
Sources & further reading
AI-assisted educational content and translations, source-checked 17 October 2026. Not an individual diagnosis or prescription. Independent aquaculture-health and native-language specialist approvals have not been supplied. Sources do not endorse AquaGrow.