I assumed that my case was lack of light acclimation. There was also stronger current than needed. I read that if the current was too strong that the sweeper tentacles would come out to look for food. I never saw that (and I have seen how long they can get) so I didn't think the current was much of a problem. After they are in there current placement for awhile, I may move them back up and if they don't open quite as well, I will assume it's due to the current.