Why Is My Aquarium Water Cloudy? White, Green and Brown Water Fixed
By Melbourne Tropical Team ยท 2 min read
Cloudy aquarium water is common and almost always fixable. Here is what white, green and brown water each mean - and exactly how to clear them.
White or grey cloudy water (bacterial bloom)
Milky white or grey water, especially in a new tank, is usually a bacterial bloom - a harmless burst of bacteria in the water column as your tank matures. It also appears after disturbing the substrate or overfeeding.
The fix is patience and good habits: don't overfeed, don't over-clean the filter, and let the tank settle. It usually clears within a few days to two weeks as the biological filter establishes. Resist the urge to do huge water changes, which can prolong it.
Green water (an algae bloom)
Green, pea-soup water is a bloom of microscopic algae, fuelled by too much light and too many nutrients. Reduce your lighting to 6-8 hours a day, keep the tank out of direct sunlight, cut back feeding, and do regular water changes to remove nutrients. A UV steriliser clears green water quickly if it keeps returning. Fast-growing and floating plants also help by starving the algae of nutrients.
Brown or yellow water (tannins)
Brown, tea-coloured water is usually tannins leaching from new driftwood - this is harmless and even beneficial for many fish, but if you don't like the look, soak or boil the wood first and use activated carbon to absorb the colour. Brown cloudiness (not tint), on the other hand, is usually fine debris stirred up from the substrate, which settles once the filter catches it.
Prevention
Most cloudy water comes down to overfeeding and an immature or disturbed filter. Feed lightly, cycle new tanks fully before adding fish (track it with our cycling tracker), rinse filter media in old tank water rather than tap water, and keep up regular water changes.