Is a 50w red nocturnal lamp enough to heat my viv, it's 20"x12"x12" W.D.H. I have it above the viv in a ZM twin dome, which is off centre and the temp sensor is in the middle approx 1-1 1/2" off the substrate. The temp has.not gone above 73 yet, which although is not directly under the hest, does seem to cool...