No difference that Tunze is not that good of a skimmer We ran one until the collection cup went MIA several months ago If space is a factor ? Look in to the DAS skimmers simple to use short and will fit about any sump. its what we use on smaller tanks a real work horse of a skimmer pound for pound and $ 4 $ its top of the line none better here is some reviews Its not common brand name
Review of the Dutch Aquarium Systems (DAS) BX-1 Protein Skimmer 
