For a 33 gal system, here is what I would recommend.
Skimmer for a system up to 50 gal (if you are not planning on upgrading any time soon)
http://www.coralvue.com/reef-octopus-bh-50-protein-skimmer
Skimmer (up to 130 gal if you are planning on upgrading system sooner than later)
http://www.coralvue.com/reef-octopus-classic-110int-protein-skimmer-183
Biopellet reactor (up to 100 gal)
http://www.coralvue.com/bio-churn-90int-reactor-with-hob-bracket
Kind regards,
Carlos
CoralVue