Protein Skimmer Counter Current - Small This protein skimmer helps prevent toxic tank syndrome; increases oxygen; helps prevent toxic build-up; it is easily adjusted; has low maintenance; comes pre-assembled and includes: two-way plastic valves, airstone and hanger assembly. Removes organics such as: water-soluble protein; amino acids; some dyes; fatty acids; fats; carbohydrates; enzymes; detergent; phoshorus; iodine; detritus; metals such as: zinc and copper; some algae; protozoa; bacteria and other organics. Sits inside the aquarium, but not totally submersed. Minumim tank or aquarium height is 11 in. Info from Pet Place