About 2-3 times a year, the sink in the bathroom starts to drain very slowly and I have to take the S-trap apart and clean out the gunk. The gunk contains some hair, but not a lot. It's mostly a black, tarry/gelatinous mess.
I used to use one of the liquid drain cleaners, but a plumber saw a bottle and told me not to use it anymore.
Are there drain cleaner products that are effective and safe? It's not a huge task to take the S-trap apart, but it would be easier to just pout something down the drain.