Thanks Jim. The hob filter houses rock rubble for the time being. I used to run carbon and filter floss but the filter floss would slowly deteriorate and end up stuck around my powerhead's impellers...so for that reason, no more filter floss. I run chemipure blue/elite occasionally.
Now the bigger purpose that the HOB filter serves, imo, is as an algae scrubber. You can see why in the video below.
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