What to put in the refugium.

[sleeman]

I have a large amount of spagetti algae (chaetomorpha) in the refuge and 4 large hermits. They are in there as a time out as they were snacking on some of the smaller blues. I have a ton of life in the algae(copeods and such), but nothing seems to have migrated into the sand.
Should this be a worry as nothing is stirring the sand bed( about 4" of sugar)?
I could drop a piece of rock in there but don't really want to cover up a bunch of sand. I also have about 5 Nassarius snailsI could move down. Any other suggestion?

Cheers,

Al