Bathtub drain leak

[Duongz]

I have a leak at the elbow of the drain. I think its the limescale/calcium bluish greenish buildup that's causing the problem but I'm not sure. I cleaned up it up the best I can. its hard to reach, I would have to cut some drywall in the basement to fully access it. the tub is upstairs.

i made the mistake of putting water weld around it but that didn't work. if i were to cut the drywall, would i be able to remove the wastepipe/tail piece from the elbow to clean it or is that permanently attached. option 2 would be to replace the tailpiece and elbow with PVC which doesn't build up and leak that much I heard. is there any option where I don't have to cut the drywall

I was also wondering if me using bleach to kill tub mold could cause the leak, I flush with water afterwards. I heard its ok as long u das u dilute. do these leaks just occur with age

 

[Terry]

The brass pipe threads into the shoe of the drain. Putting something on the outside is unlikely to work as a repair.
Most of the time, we replace the entire drain. Or you could try to remove and disassemble it, and then wrap some tape on the threads and try again.