One more quick question - what would you use to glue in the fitting if putting these into a plastic bucket since it will be curved and more likely to leak?
You can always use aquarium grade silicone sealant on any sort of "through the wall" fitting if you have leaks. Put a little around the outboard end of the part that goes through the wall, push/screw it in, then some on the inside and screw the nut down to pull it all together (*). Make sure everything is dry first or the silicone won't set properly.
With a "tube to pipe" fitting like mehjr posted, there are no nuts but you can buy a threaded connector or other short "pipe to pipe" fitting to act like one.
Bruce