ok here is the low down on what i have in both filters for media and my tank and all that....
i have a 120 gallon tank,
FX5 set-up 24 hours with ceramic rings, bio-balls, carbon, and carbon with amonia remover,
Cascade 1500 has same stuff and the pads recomened for it minus the bio balls
i have one 8" pbass,
one 10" florida/spotted gar
one 12" african pike characin
one 8" geo jurapari
in the tank i have crushed coral mixed in with my gravel to stabilize the ph, two pieces of driftwood medium size, one plastic plant
my water params are normal all the way around i dont get it