Cloudy Water in a Shrimp Tank After a Water Change: Causes and Fixes
Milky white, green or brown cloudy water in your shrimp tank? Learn what each type means, whether it's dangerous and how to clear it safely.
Photo: Chris Penny, CC BY 2.0In this guide
Short answer: milky white cloudiness after a water change is almost always a bacterial bloom. It’s usually harmless and clears on its own within a few days. Don’t respond with more big water changes. Feed less, do only small (10–15%) changes, and give the tank time.
What the color of the cloudiness tells you
| Color | Most likely cause | Dangerous for shrimp? |
|---|---|---|
| Milky white | Bacterial bloom | Rarely, but watch oxygen |
| Grey / sandy | Stirred-up substrate or dust | No |
| Green | Free-floating algae | No, but a sign of excess light or nutrients |
| Yellow / brown tint | Tannins from wood or leaves | No, often beneficial |
Why a water change can cause a bacterial bloom
A large water change, a deep gravel vacuum or a filter cleaning disturbs the bacteria colony. Free-floating bacteria then multiply quickly on leftover nutrients and the water turns milky. It happens most often in young tanks that are less than 2–3 months old.
How to clear cloudy water safely
- Pause feeding for 48–72 hours. The bloom lives on excess nutrients.
- Do small water changes only, 10–15% at a time. Large changes restart the cycle.
- Leave the filter alone. Never rinse filter media in tap water.
- Add surface agitation or an air stone so shrimp have enough oxygen.
- Wait. Most blooms clear within 3–7 days.
Warning: If shrimp gather at the surface or on the filter intake, oxygen is low. Add aeration immediately.
When cloudy water is a problem
Check ammonia and nitrite if the cloudiness lasts longer than a week or if shrimp behave oddly. A bloom that won’t go away can mean something is rotting in the tank, such as a dead snail or a large amount of uneaten food.
How to prevent it next time
- Change 10–20% weekly instead of 50% once in a while.
- Clean filter media only in old tank water, and never at the same time as a big water change.
- Feed less. Shrimp in a mature tank find most of their food on their own.
Unsure whether your water is safe? Run your numbers through the Water Parameter Checker.
