I've tried using a plunger and chemical drain cleaners,

[MikeM]

I've tried using a plunger and chemical drain cleaners, but my tub is still clogged.

Suggestion:
When working with water that contains chemical cleaners, use rubber gloves, bail out any standing water. don't plunge, and avoid splashing. For a stubborn clog, use a snake. Feed the snake down the drain or overflow pipe to the trap to break up the blockage. If that doesn't work. the problem is probably deep down in the main drain.

From: http://www.buyerschoiceinspections.com/Plumbing-Questions-Answers