Quick Answer
Brown algae, often called diatoms, usually appears as a dusty tan coating in new or low-light aquariums. It is common during the first months of a tank and is often linked to silicates, unstable nutrients, and immature filtration.
Care and Setup Notes
- Do not panic or restart the tank; diatoms often fade as the aquarium matures.
- Clean glass and hardscape during weekly maintenance and remove loosened debris.
- Check light duration, feeding volume, and tap/source water if it keeps returning.
What to watch
Use this page as a planning profile, then match the advice to your exact tank size, livestock, temperature, filtration, and water test results. If livestock are already stressed, test ammonia, nitrite, nitrate, pH, and temperature before making big changes.
Image: Wikimedia Commons fish photo used as contextual aquarium reference