For you DIY reefers, here is how my friend, beakerbob and I, made the screen mesh top:
Materials Needed:
2 - 48" (or however much you need for your size tank) screen aluminum framing material (HD, Lowes, Menards, etc)
4 - screen frame corners
1 - roll of spline material
1 - spline roller
1 - roll of screening material (see Jimsflies description above)
Cut the aluminum framing to the interior size of the top of the tank lip (minus 1/16"), insert the corner and snap together:
photos courtesy of beakerbob:
