May we count your visit with Google Analytics? It uses cookies and sends visit data to Google. You can change this any time under Cookie choices. Privacy

aquarium.guide
Choose your tank

Fish pages, lists, fit marks and tools use the tank you pick here.

Plan everything for this tank →
Menu
Aquarium guides/Cloudy aquarium water

Cloudy aquarium water: white, green or brown, and the fix

The color usually points to the cause. White or gray haze in a new or just-cleaned tank is usually a bacterial bloom, which usually clears by itself in days to a couple of weeks if you test the water and avoid overfeeding. Green water is floating algae from too much light and nutrients. Brown, tea-colored water is tannin from driftwood and harmless. Cloudiness right after filling is substrate dust.

Green water in a planted tank
Shown: green water in a planted tank. Photo: Russel Leidich/dangerousfishbowl, CC BY 3.0, via Wikimedia Commons

On this page

Open the equipment planner →
On this page

White or gray: bacterial bloom

Common in a new tank, after a big clean or when food rots. Watch the fish first: fish gasping at the surface are short of oxygen, so increase the surface movement at once. Gasping at the surface. Leave the filter media alone: scrubbing or replacing it removes the bacteria that clear the haze. Test ammonia and nitrite: if either reads above 0 with fish in the tank, change water to bring it down; otherwise feed lightly and let the haze clear. What your readings mean · Cycling.

Green: algae in the water

Free-floating algae turn the water pea green, usually from long light hours, sunlight or extra nutrients. Shorten the light, keep the tank out of direct sun, and change water; a few days of complete darkness or a UV sterilizer clears stubborn cases. Green water.

Brown or yellow: tannins

Driftwood, leaves and some plant soils leach tannins that stain the water like tea. Fish from soft, acid rivers like it. To clear it, boil or soak new wood before use, change water, and add activated carbon to the filter.

Right after filling: substrate dust

Fine particles from unwashed gravel or sand settle within a day or two with the filter running. Rinse new substrate until the water runs nearly clear, and pour water onto a plate or bag when filling. Decor and substrate.

Next checks