Matt has you on the correct path if you are adding to your 10k PC
with T5 supplemental lgihting.
Sunlight is around 5500k - 6500k. A 10k is white with a slight blue tint, 14k is more blue, 20k is bluer and actinic (420nm-435nm) is 50k.
Are you going for looks, coral growth, some combination?