What do you have so far? Looks like maybe frogbit floating, and some anubias on the bottom? You could definitely try something that grows faster so that it would break the surface sooner for you, but I really haven't looked into very many plants for emmersed growth... The only one I have done is a little ludwigia hybrid that ended up breaking the surface in the little vial it was living in and started sprouting emmersed leaves.
Also, the algae on the abubias should subside eventually, so don't worry too much about it. I am surprised that there is that much diatom coverage with no substrate... I always thought it was my sand that gave the diatoms their food, but I guess they can pop up even without any additional silicates for their shells. Maybe the rocks are leeching some minerals?