What type of lighting do you have to begin with? BTA's dont require a TON of light and in fact may move away from the light for a bit if its too intense. They are medium light anenomes, and std PC lighting is sufficienct for them to thrive. If your anenome starts to go mobile it could be either unhappy with the water flow or looking for food. If it hides its prob trying to get away from a bright light source for a while. Dont worry too much about it for a while, in time it will come out again. Just keep offering it food as it will still be hungry. Mine just moved to the top of the tank because one of my corals was hanging over it and he was shaded too much. Now its up top and has been there for a few days. Good luck.