Most people on this forum don't use a filter.
Infact, using a HOB
and bio-balls, I would be concerned about nitrate problems.
For mechanical filtration, I simply use a filter sock which gets switched out and cleaned once a week killing all beneficial bacteria. The live rock I have takes care of the nitrifying bacteria though, thus it is my biological filtration. I don't use chemical filtration unless there is a need.
I would dump the HOB
and if your nitrates start getting high, might want to do away with the bio-balls as well.