Overcrowding your tank means you're going to have to clean your tank more often and you run into the possibility of disease spreading if water is not maintained. What may be overcrowding to you may not be to somebody else. Just think about your fish and the swimming room they have. Clown, eel, and dragon don't need alot of swimming room.

I have a dragon and he is beautiful and entertaining. And I think the sand he drops on the rock adds character to the tank, looks more natural 8) . I do have to occasionally use my turkey baister to blow sand off coral and stuff. Reef is just a clean freak!! :P