[tang daddy]

The Albino acro yah there is a such thing....lol

When acros are stressed out they will expell all the zoanthelia (which is the colour)and all you're left with is a white to tan brown coral.
White sps in the wild is due to global warming and could be considered a bleaching event, if it turns from white to brown in a few weeks it's on its way to recovery or it may just slowly colour up. I would put it in a good flow area and lower out of the way of direct light to stop further bleaching once it's healthy you can move it back up slowly.