Allan writes, The purpose of the filter course is to prevent fine soil medium particles from washing into the drainage layer causing clogging or reduction of the drainage capacity of the drainage layer.
Just how much caffeine is too much? For the average person, up to 300 mg of coffee a day, or two to four cups of the average brewed coffee, is a moderate amount that isn't harmful. But once you hit more than four cups, you may experience less-than-desirable side effects.
People who drink four or more cups of black coffee a day (24+ oz.) have a 20% lower chance of becoming depressed, and are over 50% less likely to commit suicide. Drinking coffee is literally a life saver, and something I wish more people would do more often for this specific reason.