J-B Water Weld safe for Aquariums?

I use this frequently on reef and planted tanks without ill effects. I even use it with super glue gel. Just be warned that once it dries it is like concrete so don't plan on moving it!

Safe for drinking water is safe for the aquarium. Also, just my opinion, but any time you see something used in the salt water hobby, it is more than good enough for freshwater. I think you should be good.

What do you need JBweld for on a spray bar though?

Oh, well, there's something much easier in my opinion. Go to the hardware store and buy a barb to thread fitting for your hose diameter. Buy a thread to slip adapter. Buy three elbows. Assemble them together to form the same output but in PVC. Attach your pipe accordingly! I'd just recreate the part post tubing instead and avoid the issue all together.