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.
How much is too much? Up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults. That's roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two energy shot drinks. Keep in mind that the actual caffeine content in beverages varies widely, especially among energy drinks. Although caffeine use may be safe for adults, it's not a good idea for children.