Definitely go with the reflector on the t5. It looks as if its more then 12 inches from your beardie. What is your tank made out of? I'm surprised you're able to use a 90 watt bulb and get it low enough with dimmer to be at proper temp. I had to switch to the 38 watt bulb to get mine at decent temp, and brightness. My tank is a 4x2x2 melamine and have just the 24 inch t5. Looking for a reflector to boost my uvb up, and its 12 inches from my basking spot.