Having a problem with bulbs

[La_terretmoi]

I am trying to hatch duck eggs
I used 25w at first but I think it's too hot because when I check the temp it's 40°C
It's supposed to be 37.5 is it okay to use 5watts instead? Will it make a difference?

 

[igorsMistress]

Try 15, 5 isn’t enough I think based on my experiments. It does depend on the size of your incubator though. Good luck!