I've had lights crack my glass tops. The tops were for 24x18" openings on 75G and 125G tanks. I put twin-tube 36" and 48" All-Glass strip lights on top and they cracked. I would be careful, although it's not the end of the world if the glass cracks. I just siliconed along the crack and continued to use them. The plastic back strip helps hold everything together. I think the glass may be thicker than 1/8", though.