I use Plastic craft canvas, tank divider holding clips, and either aquarium safe silicone or scrap pieces of corrugated plexiglass. I use these in several tanks, some as dividers across the tank (front to back) and some just around the HOB filter output. I cut the plastic craft mesh into a strip 1-3" depending on which tank. Either silicone it in the holding clips or use scrap pieces of corrugated plexiglass to hold it in place. Make sure you trim all sharp points off the canvas or plexiglass. It will holdback water spangle. If using for duckweed, you will need to add a line of silicone between the suction cups, otherwise a little will sneak though. You can also buy this divider clips and canvas in black which blends in nicely for tanks with dark backgrounds. Cheap, easy, and customizable plant holder!