Related Clues:

• Pond's film cover
• Fish tank film
• Much pond scum
• Tank slime
• Rootless aquatic plants
• Aquarium scum
• Pond life in a gale disrupted
• Floor plants?
• Unwanted stuff in a fish tank
• Producers of oxygen
• Unwelcome pool growth
• Pool film
• Growth in a neglected pool
• Nori or spirulina, e.g
• Fish pond growth