BTW I have an eclipse hex 5 and have no water problems at all stocked with 3 dwarf guramis and 10 neon tetras. How much water ar you changing eavh week?
I'm changing about 20% a week. Just this last week I really dug into the gravel to get out all the crap so my vacuuming has gotten a little better. I was always a little nervous about digging into the gravel.
I would do 2 30% per week If I were you. Also scrub your filter pad each week, you dont really need to replace it unless it is falling apart. When you wash it make sure you wash it in tank water.