What type of bulb is it? The type becomes more critical since its relatively low powered and there is only 1. I have a 20g I keep low light plants in with a singe 15W T6 bulb. Since its only 1 bulb and not very bright I decided to go with a bulb specifically designed for plants the aqua-flora plus, and tried the t6 since it should be more effecient. There me also be a difference with the type of ballast too, mine has one of the crappy 'starters', would probably be brighter with a quality electronic ballast. Mine doesnt have a reflector either, just the white plastic around the bulb. I wouldnt expect a whole lot though, but good luck.