20G lid

http://www.cichlid-forum.com/articles/diy_tank_covers.php

That sums it up nicely.. I searched everywhere to find something, and that was about the only thing I ever found. Alternatively, you could get a piece of 1/4" glass cut to fit in the lip. At your local glass cutter, it'd probably be under $10. Get it cut to be like 2" or 3" narrower than the tank, and then put a strip of plexiglass, or that same Styrene lighting cover, and cover the 2", so that you can get into the tank to feed them.

Try the LFS, you can pick up a glass versatop for around $15.

I learned something "interesting" about my ancient 20L (20 years old and still in use. hah!) Somewhere along the line, either the dimensions changed or the brand mine is had a slightly shorter inner rim. New hoods and versa tops don't fit. They're both around oh, 1/16" too long. Great. The old hood was damaged so I kept the strip and tossed the hood. I do not know what brand mine was. When the all-glass sized one didn't fit, I had a perfecto sized one ordered. Seemed to be the same size as the all-glass so maybe the tank was an o'dell. Whatever it was, there's a full hood precariously perched on top. Fortunately, I got one of those oversized whisper internal filter stump things when petsmart clearanced them out so it's holding the hood up too.

looks like a simple setup..... ill be looking into that one