I have two SPS frags (birdsnest and monti cap) that have been under inadequate LED lighting for almost 2 months. Its been about a week and a half under my new lighting, and no change in color, although the very tips and edges of both are white (growing already?).
Agreed. Often when they do not receive enough light to saturate, they take up other means of making ATP. In this case, they are producing excess zooxanthellae to utilize nutrient uptake. To change back takes time just like it would for us to lose weight when we change our diet. HTH.