If the water in your aquarium doesn’t look quite right, you may have something wrong! Your tank water isn’t supposed to be cloudy, white, green, or yellow.
- White or gray cloudy aquarium water could be caused by dust from gravel or sand. Always rinse your substrate thoroughly before adding it to your aquarium. With sand, this can be tricky! Give your tank a day or two for dust particles to settle.
- White or gray cloudy aquarium water could be caused by a bacterial bloom or by adding too many fish too soon (before the nitrogen cycle has finished). Give the water time to correct itself — good bacteria will build up on your filter and take care of the problem.
- Yellow cloudy aquarium water may be caused by new driftwood in the tank. Tannins in the wood are released into the water — after a few months, the water will clear up.
- Yellow cloudy aquarium water may be caused by other dissolved organic carbons like fish waste and decaying plant matter. Perform more frequent partial water changes and use activated carbon in your aquarium filter to clean water and remove water smells. Change activated carbon every few months (if not sooner).
Green cloudy aquarium water is usually the result of an algae bloom. This green water isn’t harmful to your fish — it just isn’t very nice to look at. The problem crops up when you have too much light entering the aquarium and too many nutrients in the water. That can mean you’re feeding your tank too much, or not doing enough water changes. To correct this problem, here’s what you need to do:
- Move your aquarium out of direct sunlight. Sunlight can lead to algae problems AND cause temperature fluctuations.
- Leave your tank light off for a few days.
- Perform 25% water changes every day.
- Rinse or replace filter media to reduce the amount of nitrates in the water.
- Feed your fish a little less.
- Add live plants to the aquarium to compete with algae for available nutrients.
If you do all this and you still have green cloudy aquarium water, try testing your tap water. If the water is full of nitrates and phosphates, you could be encouraging algae growth. As a last resort, you can try a sterilizer to kill algae in your tank — just be sure to follow the instructions on the bottle.