cant pick up the blues

[obedear]

You will probably have to under expose the image a bit to get the pale blue to show rather than the white.
No real setting changes to make other than trying out shutter priority (Tv on canon) and going a little faster than auto would set it. Depending on the amount of light present, if auto mode asks for 1/250 try out 1/500th or a little faster until you get the colour you want in the tips.
I've been into photography for nearly a decade now, but I am basically brand new to marine/reef aquariums so I don't have any experience in coral photography, but that would be the first thing I would try.