How hot is a 400W bulb? Or a 600W?
They're alot hotter than your hot water system.
hmm... the temp in my grow is a steady 25c I guess the bulb is a "point of heat"... my tank is 70c I'm sure it must have an element or something else which a lot of heat...
I'm sure the bulb is a damn sight hotter though... I won't be sticking my tongue on it to find out anytime soon