who uses what halide bulbs?

[tgoeujon]

i kinda figured it would be a color change but what im trying to figure out is if it will be beneficial to my corals or not, if i dont like the blue i can always go back.

[bowkry]

right now I have one side xm 15000k 400 watt and the other side xm 20000k 400 watt I am want to see what has better color and coral growth. I think the 20000k is way too blue. The coral growth look like the same.