Planted Tank Guru
Join Date: Sep 2004
Location: Garden City, KS
^ While I agree with that post, I will also say that liquid nails is what I used to glue my light to the inside of a plastic hood for my 5g. It holds up to extreme temperature fluctations, and high humidity levels. I went through this ordeal a few months back, and I even started a similar thread to this one, and the best responses I was getting were to use epoxy. That was just a bit more work than what I needed, though, because I didn't care if it came out messy (it wouldn't be visible!). But marine epoxy is probably the absolute best adhesive you could use for this type of application.
I still recommend liquid nails, though! It worked for me. Just goop it on there, let it dry somewhere for several days to make sure it cures, then it's like cement!