Summary:
I won’t bore you with the nitty gritty principles of how it works but it is an integral piece of equipment for captive saltwater systems. To summarize it all, protein skimmers incorporate air into water in a manner where the resulting foam, consisting of dissolved organics, is pushed up the tube and collected in a cup.
Based on the principles of the venturi effect, water pressure is reduced when it flows through a constricted section of pipe. A pump pushes water through one of these devices and air enters at the restricted portion, mixing air and water as it enters the skimmer. Finer air bubbles are created if a pressure rated pump or high volume flow biased pump is used.
Similar to the venturi style, the pump is placed after the venturi and the air drawn in are coarser than the venturi and a high pressure pump is not required. The impeller blades are replaced with a disc of pins pointing parallel to the flow of water into the pump, a disc of a mesh material or pins radiating from the centre that has smaller pins/stubs sticking out of the radiating pins.
A high volume of water is passed through the top of a tube under pressure via a pressure rated pump. The tube is filled with “bio-balls” and as water is forced into the tube, the “pins” of the bioballs “split” the stream of water as it passes down the tube. In the process, air is incorporated into the water.
Similar to downdraft and venturi style skimmers, high volume and pressure is required. A foam nozzle (Beckett 1408, from which the name is derived) is used to incorporate air into the stream of water as it passes through.
Water is “power sprayed” above the water level in the protein skimmer reaction box.. Similar to the downdraft skimmer, when water is sprayed onto the water surface, air is incorporated into the water.
This is where it all began. Like typical airstones used in freshwater aquariums, they use limewood or basswood where the fine pores create the desired ultra fine bubbles.
For today’s marine hobbyist, the popular styles are aspirating needlewheels, Beckett and downdraft style skimmers. Choosing which style of skimmer depends on spatial requirements of the skimmer, access for maintenance/service, power consumption, noise level, etc. Choose the brand and any supporting equipment that has a good running track record as well as customer support in your area should any issues arise.
Happy Reefing