Inches. -. A shoe size is a numerical indication of the fitting size of a shoe for a person. Several different shoe-size systems are still used today worldwide. In some regions, it is even customary to use different shoe-size systems for different types of shoes (e.g., men's, women's, children's, sport or safety shoes).
Types of Algae. Brown Algae (Diatoms)  This is the first type of algae that begins growing in a new aquarium. It usually grows on the gravel and glass. Unlike other types of algae, this type requires silicates in order to grow. By increasing light levels, this type of algae can be replaced by the more beneficial green algae. Brown algae can easily be scraped off the glass.
There are several thousand known species of algae in the world and they occur in many different colours and forms. Algae can for instance be green, blue-green, brown, red or black. Some types of algae will drift around in the water, while others grow attached to a surface, e.g. a rock, coral or plant leaf. There are also types of algae that float on the surface since this is the place where they can receive the most light.