I have a slow leak coming out the center of the back panel on a plywood tank I finished just 5 months ago. Obviously I will have to drain the tank, but what do I do now. Its not coming from a seam its just right in the middle. Does this mean that it wasn't sealed enough to begin with and its rotted through? Could this thing explode on me at any minute? Do I have to replace the panel? Or just re seal? Any help is much appreciated.