Which "K" for my MH bulbs?

[GMGQ]

If you're just starting a new reef, you'd want 10K to promote growth.

Once your corals have reached a satisfactory growth level, Then move on to 14K or 20K. The blue light makes the corals' colours pop out (almost like black light and fluorescent clothing), but growth will be noticeably slower than 10K.

I also agree with what Muck is saying about having bulbs with enough PAR to penetrate the depth of your 190gal tank.