This was what I happened to know about keeping pods' population from decreasing in the display tank. I left 2 sheets of plexi glass (18x20) stand against the back tank wall to prevent it from getting scatched by the LR, and it turns out that I've created a perfect home for pods to grow behind the sheets (there's a little tiny gap between the plexi sheet and tank wall) My Lawnmower benny goes crazy when he sees pods behind the sheets but he can't touch them. The main population of pods live behind the plexi sheets during the day and they're swimming all over in the water column and sand bed at nite. Some pods still live out side on LR and SB and they are get eaten by my fish very quicky. However, my pods' population won't decreased tremendously.