Hi. I recent got a powersun 100w mounted in a zoo med deep dome lamp fixture and was wondering if it should be hanging above the screen or if it was OK to set it on the screen top? I have an exo terra large low(36"x18"x12"). With the the light on the screen it is 12" to the cage floor, but the basking branch is up about 6". When my beardie is on the basking branch the light is about 6" from his back.