Place them directly in the light and the colors should come out nicely. It will take at least a month, there is nothing that will make paly's brighten immediately. You can also try adding vitamin C, but I am new to it, I haven't ran it on my main tank yet.
Metal Halides tend to lose their "umph" after about 8 months and 10k tends to make zoa's turn brown. I keep my corals under 14K's which put out a bluer light.
Your alk should be measured in DKH and be between 7 (near natural sea water) and 10, sometimes mine is as high as 11. I hope this helps you out some.