OK, a few things... Your po4 levels are not going to harm corals, let alone kill them, neither is not enough light going to do it that quickly. Also your Alk level is fine, there's no reason to lower it. The question is, is it stable?
Primes can light a large tank(AI has a large display lit by them alone), but you need enough of them. I wouldnt use one to cover more than 12" so on a 4' x 2' tank I'd want 8.
I also don't feel light acclimating is necessary most of the time. Trying to move a low light corsl into high light is one thing, but most sps are likely coming from similar or higher par.