Cloudy Aquarium Water
Fix cloudy aquarium water: tell bacterial blooms from dust and debris, check ammonia and nitrite, clear it safely, and stop it coming back.
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Troubleshooting
Green Water
What causes green water, whether it is harmful, and how to clear it with a blackout, UV sterilizer or other methods, then keep it from returning.
Brown Water
Why aquarium water turns brown, from driftwood tannins to waste problems, how to check water quality first, and how to clear or prevent it.
White Fuzzy Growth on Wood
White fuzzy growth on new aquarium wood can look alarming, especially when it appears only a few days after you set up the tank.
Fish Gasping at the Surface
Why fish gasp at the surface, what to do immediately, and how to find the cause, from low oxygen and ammonia to heat, medication or gill disease.
Shrimp Suddenly Dying
When several freshwater shrimp die within a short period, treat it as a water-quality or exposure problem until evidence points elsewhere.
Snails Escaping the Tank
Finding an aquarium snail above the waterline does not always mean something is wrong.
Algae Outbreak Guide
An algae outbreak is a rapid or persistent increase in visible algae that overwhelms the amount you normally tolerate in the aquarium.
High Ammonia Emergency
What to do in a high ammonia emergency: confirm the reading, reduce exposure fast, find the source, restore the biofilter, and prevent a repeat.
Low Oxygen Symptoms
Signs of low oxygen in aquarium fish, why dissolved oxygen drops, what to do in an emergency, and how aeration and surface movement prevent it.