Glossary: H

Hair Algae

Home Depot, home improvement store

An animal that eats plants. Herbivores such as snails are an important part of a reef tank because they help keep algae under control.

Hang on back filter

Hope this helps (forum lingo)

A device used to measure the specific gravity of seawater. The most common types consist of a clear chamber with a floating needle.

Lacking or defficient in oxygen