That's what mine is. I couldn't get the 50 to warm by 40 up enough, but I have yet to get a digi thermometer, so I can't really say for positive sure. It's a little tight right now, getting the new setup stuff for da babies.i am using that same bulb i have a 75w in there right now i have a 50w too but it doesnt get the right temp i also use the 75 in the summer too because i use my air condistion and my tank is a 40gbreeder tank