CO2 isn't going to get the plant to carpet. The lighting conditions are what makes plants grow that way. Think of it this way, plants are growing towards the source of light. If the lighting isn't sufficient, they will grow towards the light. So in lower light conditions, glosso will grow taller. In higher light, they don't need to reach towards the light so they'll grow lower along the substrate.
so in short,glosse wont carpet in low light conditions.