Foxface rabbit fish will eat valonia. Mike Roby kept one for years.
It is not really a viable option for such a small reef, but if you were to displace the rock in a larger system for cleansing it may work for you.
Scientific Name: Siganus vulpinus
Other Scientific Name(s): Amphacanthus vulpinus, Teuthis vulpina, Teuthis vulpinus, Lo vulpinus, Teuthis tubulosa
Common Name: Foxface
Distribution:
Diet: They need aquarium algea and frozen herbavore diet, but also eat flake food and like brine shrimp as well, they are very rubust eaters and are not picky but do need their greens to stay healthy
Temperament: Can be kept with community or agressive fish, they are real easy going and other agressive fish don't seem to bother them because of thier poisonous spines
Sexing:
Breeding:
Special Care:
Other Comments: The Fox-Face Rabbbit Fish are amongst the most sturdy, disease-free animals the hobby can get; they are generally the last in the tank to die from any given cause.