Set an aquarium in a sunny location in your home such as near a window. Avoid placing the aquarium in a location where wind is not limited.
Place rocks at the bottom of the aquarium. Fill the aquarium with water and place an aquarium thermometer in the water. This will allow you to determine the temperature of the water. Algae plants and growth enjoy temperatures above 70 F.
Position live plants at the bottom of the aquarium to promote algae growth.
Add pure sugar to the aquarium as foods that are high in sugar promote algae growth. Add sugar daily to help grow algae.
Scrape the algae from the aquarium by hand or with a knife and move it to a smaller location, such as a jar.
Fill the jar approximately halfway with water from the aquarium. Place the smaller jar in a cool location with reduced light to continue algae growth and leave the jar untapped. Promote growth by adding sugar to the jar.