Some toilets just don't have enough flushing power. As in, when you flush the toilet not all of the, er, stuff, goes down. As a result you have to flush the toilet twice, wasting water and your time.
Turbo charge your toilet flushing by checking out the tip in this video, which will help you increase water pressure. You'll learn how to make a flush that's too strong weaker and how to conserve water, as well.