change in lighting could do it. 18" off water surface is ALOT in my expirence,even for 250s. Are you planning to slowly adjust them lower and lower so that you dont bleach out your corals?? I know most keep their MH about 8"-12" off the water.
Can you take a pic? being inflated isnt a bad thing infact mostly all of my euphylia are inflated and puffy --its the kind of corals it is. if its dull and colorless then you have lighting issues. Its soooo difficult to tell you whats wrong without a picture. Post a pic and tank levels and alittle history then maybe we can give more. otherwise, we're all just guessing in the dark.