Jeff721
Members
Eheim filters are different in the gph rating from what I understand. They house the appropriate amount of filter media for the tank volume for which they are rated. But they don't provide the flow which we deem to be correct. So in turn more of your water spends more time with the filter media, but doesn't turn over as often.
If you know about photography it is a simple concept to get. You can expose more light to film in two ways, one is to use a larger opening, thus allowing a flood of light to cover the film. The other is to use a longer exposure thus allowing more interaction time with the film.
Both produce a picture, the former is less detailed but faster. The latter is very fine detail but slower.
Basically the "5x Tank volume Per Hour" rule goes out the window (mostly) with eheim filters. Want more flow, add a powehead. Eheims are great for planted tanks and fine substrate that you don't want a monsoon in your tank.
