Drano Max Gel, made by SC Johnson, is heavier than water, and usually sinks straight to the source of the clog. Gel sitting on top of the water is an unusual occurrence. Clogs in pipes are caused by clumps of hair, grease, food or other debris. A drain cleaner uses powerful chemicals to break down these clogs. If Drano fails to clear a clog, though, mechanical means can usually break through it.
Read the package directions to ensure that you used enough Drano Max Gel. For a serious clog, pour an entire 32-ounce bottle in the sink, or half a 64-ounce bottle. Wait from 15 to 30 minutes, or up to overnight.
Flush with hot water and repeat if necessary. If the sink is still clogged, watch the level of the water to see if it is slowly going down. If so, allow it to drain. Once no water remains in the sink, place a plunger over the drain. Stuff a rag into the other drain if you have a kitchen sink, or into the overflow hole of a bathroom sink. Covering these openings increases pressure, helping a plunger work more efficiently. Press the plunger vigorously up and down to release the clog.
Use an auger to fix a sink if standing water remains. Place a bucket under the sink trap to catch the standing water. Unscrew the slip nuts at the bend in the pipe. Inspect the trap, which is the curved part of the pipe, for clogs. Use a plastic implement, such as an old toothbrush, to dislodge the clog.
Loosen the auger setscrew to pull out 18 inches of cable. Insert the cable into the drain line and push it until you feel resistance. Tighten the setscrew slightly and turn the auger again clockwise to move it forward. Continue the process of loosening, tightening and cranking the auger to remove blockages from the pipe. If you feel significant resistance, pull the auger out to remove hair or other debris.
Remove the auger and replace the trap arm and trap. Allow hot water to run through the pipe to remove any lingering debris. Use a plunger to break up remaining clogs so water runs smoothly.