tank looks really good
But you should slow down on adding stuff for sure. I would not add the clown in for another couple/3 weeks. Adding 10 fish at once will definately change the bioload, so the bacteria is gonna have to bounce back before you put in your clown. your tank seems to be a 135 gallon tank...thats a large tank and with lots of rock you'll have less of a problem with bioload needing to bounce back..but still just take it slow. I know you'd hate for that clown to not make it due to a simple little mistake like that.
Like how my 55 broke and i rushed all the fish and stuff to my 40 breeder...everything transfered over fine luckily...and then my sixline got sucked up a powerhead cuz i was stupid and didnt put the cover over the intake.
Now that probably doesnt have much to do with what i'm saying, lol, other than just make sure you eliminate as many possibilities as you can as far as stuff that would be harmfull. I didnt and it came back to bite me.
And again...for the tangs just take it slow. (them especially since they're bigger).
But you say you want a sand sifter....i strongly suggest the diamond goby. Not the absolute greatest looking fish in the world (not ugly, i just dont really care for plain colored fish much) but he did his job very well in my 55. Sand was like an algae carpet..added him and a few days later it was white again