Bath tub slow to drain

I made a tool out of a section of garden hose and a bicycle inner tube that fits in my drains. When ever they become slow to drain I insert it into the drain and turn on the hose. The water under pressure cleans the drains. It seems like I have to do this every other year. I also have the "zipit" drain cleaner but that does not remove soap scum buildup only hair if you can fully insert it.