Related Clues:

• Sea moss, for one
• Bathtub woe
• Pond film
• Ugly film
• Pool-owner's problem
• Bathtub dirt
• Icky residue
• Pool growths
• Phycologist's study
• Surface matter
• Aquatic plants
• Organism that can be brown, red or green
• Pond problem
• Soap ___ (shower buildup)
• Tank top?