Thanks, yea i have about 3/4 of the screen lid covered with plexi. My questions was more of is the medium size UTH alright, or should I go back to the Larger sized one and use a rheostat/thermostat if it too hot for now. Im worried that the medium won't be enough come winter. Based on my temps I supplied using the two, what do you think. I can return the medium and get the large back no problem, or should I just stick with the medium.