My cambombas are growing like weeds, i have to trim them often to keep them in check..but the only thing is i've noticed they've all gotten..less dense? The leaves have grown further apart and looks less bushy than they used to...am I missing something? I add liquid fert weekly, and they all have no problem getting taller... they've just become more "barren" looking. My lighting is 15W, and they're in a 10 gallon tank with the temp at 27 C..