Now you tell me! lol my son and law told me try it so made my 4th trip to Lowes and I'll be damned if they didn't work and right away! Im flowing again.Those drain cleaning bladders work sometimes when the clog is down river like you have.
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Creates pressure in the rubber to seal off the pipe then the small slit in the end opens up and allows water to flow out pressurizing the pipe .
Another thing I have done is just use a garden hose If you can snake 50 foot of hose into the drain.
I have a heavy duty garden hose that does not like to bend much.
Good luck to ya.
I had 3 different sizes of those bladders at one time.