Guide
Cloudy water and bacterial bloom
Milky water is common in new or disturbed tanks and is often temporary.
What a bacterial bloom is
A bacterial bloom is a temporary explosion of free-floating bacteria. It often appears as white or gray cloudy water, especially in new tanks or after major cleaning.
Common triggers
- New tank startup.
- Overfeeding and excess waste.
- Deep substrate disturbance.
- Large filter/media changes at once.
What to do
- Test ammonia and nitrite immediately.
- Reduce feeding for 24–48 hours.
- Do partial water changes if parameters are unsafe.
- Keep filtration running and avoid overcleaning media.
- Be patient: many blooms clear in a few days to two weeks.
What not to do
Avoid repeated full cleanouts or frequent full media replacement. Those actions can make instability worse.