Custom screen cover: an example of a custom screened in top made using mesh from Bulk Reef Supply (mesh is clear for max light) and window screen edges/corners from Home Depot. Use a spline tool to push mesh into frame. Netting kit: http://www.bulkreefsupply.com/diy-aquarium-screen-top-kits-1-2-netting-1.html. 50"=4.1feet. 15.5'=1.2feet. About $40. Have it sit on inside rim of tank.