Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
If yu go with one of the 'plastic' materials it should be thick enough not to sag. This added thickness might reduce the light.
I like glass for a top because it seems to clean up better than any of the 'plastic' materials. If needed I can scrape it with a razor. Sure cannot do that with acrylic or plexi of any sort!