few questions actually lol-
for those who use CHE's do you leave them on all day/night?
what wattage do you think i'd need for a 90 gallon tank?
where in the tank should it be placed - in the middle? Cool side? his basking side is warm enough.
I have mine on all the time to raise the ambient temp. My apartment has 10 ft ceilings so it's expensive to keep it super warm in the room. I live in CT and it's getting chilly here. I keep mine in the middle to provide a temp gradient that goes from highest to lowest. So from left to right it goes from basking (basking light) to mid range (CHE) to cool side (no heat source). We check the temps with a little temp gun to be sure all is well. If it gets chilly on the cooler end I turn up the CHE a bit. We have dimmers on our basking light and CHE. I got the ceramic socket lamps that have dimmers attached. As long as the wattage doesn't exceed the socket you are fine. Ceramic is great for high temp heat sources. With the dimmers you don't have to worry about it being too strong since you can control it.
I used a low wattage CHE overnight during the winter because the tank would dip into the 50s without it. I had it on an adjustable lamp stand and set it about 25'' above the bottom of the tank which put the temps to around 70 on the cool side overnight. If I had it to do again, I'd look into a heat projection light because they burn much cooler than the CHEs do. http://www.reptileuv.com/shop/index.php?main_page=product_info&cPath=75&products_id=196
Yeah as long as it's a metal lid. They get VERY hot so you don't want it to come into contact with anything that will burn or melt. That's one reason I prefer to hang them from a lamp stand.
so far i didn't have to use the 150 watt at full power but it is on the metal screen at the moment. I may eventually get a stand for it, but it worked in a pinch, thanks!