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.
Though it is impossible to recommend a safe range of caffeine intake, most studies show that adults can take in 200 to 300 milligrams safely each day. This is equal to two to four cups of coffee. However, that might be too much for many people, who could feel jittery and on-edge after only one cup.