I put in the required amount of glass media into my filter (details in sig). It said I could use less weigt measures (15%) because the glass media is lighter and so I have the required volume. I'm left with about 25cm (10 inches) of gap from the top of the media pile to the top of the filter. As my pressure is only 13 psi and my pump is powerful enough, could I add more filter media to get improved filtering or should I have a set gap at the top of the filter? Maye I have about an 5th of the filter volume as space.
(I might need to add more detail but not sure what data to provide)