I have never had that problem, I have 2 and they are front and center since I placed them there after split. As gig'em said if you provide a place with a good foot hold, mine like high lighting they are directly under 150 MH, mine prefer strong intermitent flow. If they are in a spot you don't like you can direct a powerhead at them which will usually make them move. There is no magic, they will choose the spot they like. I have found that once situated in a spot they klike, they only move if they are unhappy or as in my case when they are going to split. good Luck : )