I have seen this tank in person, it is absolutely astounding. Could not find the main threat for this tank if there is one, maybe someone could direct me.
Anyways I went over to Dave's last night and checked out his tanks. They are the most natural looking reef I have seen anywhere thus far. Corals growing on corals, competing, adapting, and for the most part THRIVING. He has a literally uncountable amount of species of coral, all sps. His fish are very old for what we consider old (im talking 5-10 years! for some of them!). It looks like Dave stole 325 gallons of coral/rock/water/fish from off a reef in the wild and plopped it in his living room! His frags are absolutely gorgeous. As a new comer to this hobby I am proud to say I am reinvigorated with interest (if I wasn't already addicted ha ha) after seeing this tank. This gives me a goal to work toward as a hobbyist myself and being as young as I am (24) I have to say he has quite an accomplishment growing in his living room. Just thought I'd give my respects and 2 cents about the tank in the video above.