I hired the liquid one
Our bathroom sink was all clogged up. Water would back up and take half an hour to drain out. We poked around in it with the snake thing that was under the sink, we tried a plunger, etc. When I was at Target I thought I'd give some drain cleaner a try, so I bought a bottle of Liquid Plumber for $4. It said to pour half the bottle in and wait 15 minutes, then flush with hot water, which I did. Nothing much happened, but the water did drain out a teensey bit faster. The next day I did it again with the other half of the bottle I had left, and it worked! the drain is as good as new.
