The red ones are decent and do a good job of upping overall ambient temps and you can leave them on 24x7 - just watch it doesn't leech your humidity away. Use the decent ones that are made of red glass not the cheap coated "party bulbs" as the red coating will thin out from the heat and eventually the light will shift into the spectrum visible by snakes - and leaving THAT kind of light on all night is bad stress. If you get zoo Med bulbs see if they will test them in the store for you - not sure why but I have bought SO many of that brand that blew the filament the first or second time it was turned on.