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.
Where there is water, light and nutrients there is algae. In an aquarium, algae may come from many places, through algae spores in the air or in the tap water. They can be introduced into an aquarium as small filaments attached to plants or even in the digestive tract of fishes. Not all algae in the aquarium is necessarily bad, a certain amount is inevitable.