20k not blue enough

[bv_reefer]

i'm running a 20k 400-watt XM bulb over my tank, and i'm still not getting the ''deep blue'' i was hoping for at all, everything around the tank is blue but not the tank so much, i guess you could say it's kind of in between 10k and 14k really. it's about 10'' or so from the water surface and the reflector is kinda crappy, could this be the reason? i was really hoping for a deep reef kind of blue..