House is 35 years old and the shower tub (2nd floor) combination drains very slow.I have took off the drain screen and noticed that about 2 -3 inches below screen the drain has something that turns the water to drain. I cannot not snake from here because snake would not get past this piece. Any advice. Will sodium Hydroxide help if poured down lines? Will it do any damage?

House is 35 years old and the shower tub (2nd floor) combination drains very slow.I have took off the drain screen and noticed that about 2 -3 inches below screen the drain has something that turns the water to drain. I cannot not snake from here because snake would not get past this piece. Any advice. Will sodium Hydroxide help if poured down lines? Will it do any damage??

"I cannot not snake from here because snake would not get past this piece."
Sure you can. That return bend is called a trap and you must push and crank your way past it with the snake. It's a little rough to get past it but once past it put out about 15 feet more snake.

Shower drain clogs are usually rotting hair wadded up with grease ftom the soap. Let me show you how to snake out the drain line. First remove the strainer,(TIP: put the screws in the soap dish. They will be hard to replace if they go down the drain.) Now work your snake past the trap and 15 feet beyond. When you pull the snake back it should have the hair that was clogging your shower on the auger tip. Now pour 1/4 gallon of bleach down in the trap and let it set over night. Next morning pour a pan of boiling water down the shower to clear what's left and make your drain smell nice. Good luck tom