I have a CPR Bak-Pak 2 HOB skimmer that has a chamber for Chaeto or Bio Bale media. I had good luck with it when starting out, but upgraded to a sump and wouldn't be without one now. I've got at least 4 complete Rio pumps and spare impellers. It was used on a 75G tank and has 2 skim chambers that seemed to produce really well. I have Chaeto to get you started. I think most would recommend you add a sump for the benefits of macro algae, but if a sump isn't possible at least this unit has room for Chaeto or Marine pure blocks. PM me if interested in it. Open to trades and I've got a few HOB overflows if you want to try a sump without having to drill your tank. Best of luck with whatever path you choose. Located in Foxboro.