There are several methods of opening a slow shower drain, from using a plunger to pouring chemical cleaners down the drain. Another alternative to freeing a slow shower drain is to run a plumber's snake tool down the drain in an effort to remove a clog. No matter the method you choose to open the slow shower drain, you should follow the action by running plenty of hot water down the drain to make certain the clog is completely removed.
A slow shower drain is often the result of a hair clog in the drain pipe. The hair can usually be removed by placing a rubber plunger over the drain and giving a few pumps or up-and-down motions of the plunger handle. You can usually pull the hair out of the drain after the plunger sucks it up and out of the drain pipe. You may want to use rubber gloves since the rotting hair can be very slimy and smelly when it comes out of the drain pipe. You may have to repeat this step several times until no debris comes out of the drain.
Occasionally, you can remove the drain cover from the shower floor with a screwdriver and simply reach into the drain with a pair of tweezers to remove the hair clog. This will often free the slow shower drain, however, the clog may be too far down to reach. Liquid drain cleaner or opener can often be used to remove the clog, thereby freeing the slow shower drain in a matter of minutes. This can be accomplished with standing water in the shower floor, however, it is best done with no water in the shower. Sometimes, a combination of the chemical drain opener and a plumber's snake tool will work the best to remove a clog.
For a severely clogged shower drain, you may have to gain access to the drain pipe from underneath the shower and remove the S-trap. This is usually accomplished with your hands on a plastic drain pipe system and with common hand tools on other types of systems. You may want to place a bucket under the S-trap to catch the water that will drain out of the shower once the trap is removed. Any type of clog can usually be pulled from the drain once the trap is removed.