acan and favia corals no longer showing tentacles after changing light spectrums

[majicman]

Hey everyone im new here and i have a question has anyone ever noticed a acan or favia coral not expose the tentacles when feeding after going from a 10000k bulb to a 20000k bulb as mine are no longer showing after this change instead they are now only showing a small hole in each mouth when feeding before they would actually have tentacles that would grab the food and pull it into the mouth nothing else has changed and all the water cemistry is good as it has always been tanks been up for over a year and this only has happend since the bulb change it is a 400 watt metal hylide bulb

 

[organism]

Is it the first time you changed the bulb in over a year? If so your new bulb is probably dramatically brighter than your old one, you may want to cut down your light cycle to acclimate the corals to the new lighting.