Guide
Why is my aquarium water cloudy?
White, grey, or green cloudiness can mean different things. How to tell and what to do.
- White or milky often means bacterial bloom in new tanks; usually clears with the cycle.
- Green means algae bloom; reduce light and nutrients.
- Do not over-clean the filter or overdose clarifiers.
White or grey cloudy water
Often a bacterial bloom in new tanks during cycling. It usually clears as the cycle establishes. Do not over-clean the filter. Grey can be dust from new substrate or stirred debris.
Green cloudy water
Usually a free-floating algae bloom. Reduce light hours, do partial water changes, and cut back on feeding. See our green water guide.
Keep learning
Stable aquariums come from consistent testing and patient stocking. Continue with our water parameters guide, how to cycle a tank, and combining fish safely. For logging and strip scans, see App-aquatic.
Log parameters, scan strips offline, and run stocking checks with App-aquatic.
Get the free appWhite or grey cloudy water?
Often a bacterial bloom in new tanks during cycling . It usually clears as the cycle establishes. Do not over-clean the filter. Grey can be dust from new substrate or stirred debris.
Green cloudy water?
Usually a free-floating algae bloom. Reduce light hours, do partial water changes, and cut back on feeding. See our green water guide.
How does regular testing help?
Regular testing lets you catch ammonia, nitrite, and nitrate shifts before fish show stress. Log results over time to see trends, not single snapshots.
More guides · How to cycle · Green water · Water parameters · Get the app