well, i saw one guy's setup was he has a small powerhead connected to a rainbar underwater... then whenever the sand slips down it'll be blown back into the *shore*..
kinda like the theory for the beach, but getting the right flowrate for the pump should be quite a challenge.. haha...
it looks something like this... *Sorry for bad drawing.. just anyhow 1*
black part is the powerhead..
sand and water quite obvious...