I'm actually kind of surprised, as Nassarius snails are primarily carnivores, and go for meaty stuff, decay, and usually don't have much interest in algae.
Maybe drop a few pellets or meaty food away from the area you place the algae? I agree the blenny is defending his food source, but the snails shouldn't be competing for algae, unless they are out of food they want.
Maybe drop a few pellets or meaty food away from the area you place the algae? I agree the blenny is defending his food source, but the snails shouldn't be competing for algae, unless they are out of food they want.