Why Water Drips From an Aquarium Light Hood

Aquarium lights contain condensation hoods.

Almost all aquariums contain condensation hoods. These hoods, made out of plastic or glass, prevent water from interacting with the lighting system or light ballasts. This is a protective feature that is designed to trap water through condensation or block splashes from fish.

Condensation

Condensation is the act of liquid water evaporating and collecting again in a liquid state. This can happen inside an aquarium, which is a microclimate.

Bubble Condensation

Some aquariums contain air pumps that provide oxygen to fish. These tiny bubbles break on the surface of the water, leaking thousands of tiny splashes on the condensation hood. Eventually, enough water builds up on the hood that it begins to drip back into the aquarium.

Heat Condensation

Aquariums are almost always heated to maintain aquatic life. That can mean water is much hotter than the surrounding air. When that happens, water can evaporate and collect on the condensation hood, which is usually much cooler from the outside air. This can lead to water collection and dripping, even when no air pumps are in the tank.

References

• Moonlight Aquatics: Fitting the Condensation Tray and Hood
• University of Illinois: Condensation