"is this necessary?"
When I got my Coralife PC
light, there were mulitple places in the installation that said specificially not to use it without a glass top. I am sure people use the lights without glass tops, but the glass top really adds another layer of safety, and helps reduce evaporation, and keeps fish from jumping out of the tank. It also shields the tank water from the hot light (which would cause more evaporation), and at one point or another, water will be splashed up on the light from a fish or odd current of water. I think if you had the light on mounting legs a few inches above water you would be ok though. I use a glass top and have my PC
a few inches above the tank.
"why wouldn't it be included?"
So they can charge you extra for it later
2x Sunburst Platys (2M, 2F) // 3x Neon Tetras (?) // 2x Cherry Barbs (1M, 1F) // 2x YoYo Loaches (?) // 1x Bushy Nose Pleco (M) // 1x Clown Pleco (?) //
-30# Live Rock
-Mixed Snails (Nassarius // Cerith // Astrea // Black Turbo // Mexican Turbo)
-8x Blue Leg Hermit Crabs // 1x Banded Serpent Star // 1x Cleaner Shrimp
-1x Royal Gramma // 1x Percula Clownfish
-2x Mushroom Leather // Metallic Green Star Polyps // Pulsing Xenia // Striped Xenia // Blue Mushroom
-Remora + Maxi-Jet 1200 // 2x Maxi-Jet 600 // Maxi-Jet 400 // Visi-Therm Deluxe 50 // Current USA Orbit 2x 40w PC