Everything looks good. I think you and the seagrasses will appreciate the halide, for sure. Until I see better daylight/warmer spectrum LEDs on the market, metal halides will continue to be my preference for these sorts of tanks.
Don't feel left out on species. I think your tank really reflects the habitat nicely and it is something that isn't seen as often as it used to be. For a while there "biotope" and habitat-specific tanks were all the rage, whereas previous dutch-like displays of corals and algae from various habitats were popular prior to that. I'm seeing the latter really come back into popularity again, which is interesting. I think it is great that this is a focused display. Heck, if I didn't have my clownfish for so long, I would've done a Caribbean display to begin with, focusing solely on species found in seagrass beds there. I just don't have the heart to get rid of my puppies--er... at least they sorta act like 'em.
Well, I got the halide & the ballast is broken. The seller is giving my money back tomorrow. He's as surprised as I am. He won the light at a raffle & just never opened it. He's got a 350g. So I'm back to square 1 with this tank. I'll keep looking for a halide, as it's the best choice, but my 4g nps pico sprung a leak & I had to buy a small tank to transfer all the inhabitants.
That's exactly what I like about this tank. Of course I've got my "collection" tanks too, but it took more effort to set this tank up than the others.