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.
A normal dose of caffeine is generally considered to be 100 mg, which is roughly the amount found in a cup of coffee. However, more than half of all American adults consume more than 300 mg of caffeine every day, which makes it America's most popular drug. Caffeine is generally consumed in coffee, cola, chocolate, and tea, although it is also available over-the-counter as a stimulant.