im not sure how you tell what the difference is in rtn from just straight bleaching...ive kept sps coral for so many years and not to long ago one of my acros just shut down,or started bleaching,,nothing else did ot has..i have a pretty nice sps reef and i dont know what happen,guess it just wasnt happy anymore....this one didnt start at the bottom...really started all over..i frag corals all the time,i have to,but the ones that do the best for me i have let get relaxed i guess you could say for awhile and then start the cutting....