Related Clues:
- Plant in a pond
- Food for some fish
- Bit of fish tank gunk
- Green growth in a pool
- Seaweeds generally
- Bit of pond growth
- Diet for some aquarium fish
- Pond's film cover
- Simple plant, plankton or seaweed, say
- Fish tank film
- Much pond scum
- Tank slime
- Some of the natural gases found in seaweed
- Rootless aquatic plants
- Aquarium scum