The Octo Classic 100-HOB Hang-On Protein Skimmer is the third of five Hang-On Protein Skimmers. The Classic 100-HOB is rated for Aquariums from 50 litre, and up to 400 litres.

The Octo Regal 150-S Protein Skimmer is the first of four models of space-saving, high quality-constructed Protein Skimmers. The Regal 150-S Protein Skimmer is rated for Aquariums up to 800 Litres.