German Blue Rams

[PortWash]

I am in the process of raising the level in a corner of my tank and building a cave into it. Is there anyway to coax newly added Rams to make that their home short of covering up all other possible home choices in my tank?

Also what would the optimal size approx. of the cave or if you have rams what is the size of the home that they have made in your tank. Any input would be greatly appreciated.