you still shouldn't keep a shark in your tank even if it only grows 11"...
You have a 125... and it's reef..
Well, consider this. After you are done with all the LR that is necessary for a Reef tank, and all the coral, and inverts, and other fish--->you really don't have 125 gallons.. And even if you did, I still wouldn't put a shark in there. They need tanks with rather large footprints of FREE swimming room, especially to make turns. Imagine how an F-18 turns in the sky...makes a big swoop..it can't just turn on a dime like say a Cobra attack chopper. If you are serious about keeping a shark then get a larger tank...at least 280..with minimal LR a WIDE footprint, sand substrate..and kick ass life support systems as sharks have heavy bio-loads.
Reef + shark = disaster. The technology or space just isn't there yet for us to be able to recreate what is in nature already.