Some consider the protein skimmer a critical piece of equipment for the reef aquarium, others like them for saltwater aquariums in general. While no piece of advice in the marine aquarium hobby is without controversy, the various types of protein skimmers have much to recommend them. A protein skimmer directly removes organic waste from the water column to improve water chemistry. The venturi skimmer is an important variation on the protein skimmer.
Protein skimmers use a process called foam fractionation to remove organic waste from aquarium water. The process is pretty simple: Protein skimmers generate many tiny bubbles; as these tiny bubbles rise through water, they pick up organic compounds like proteins, lifting the contaminants to the surface, where the bubbles form foam. You can skim and discard this foam, preventing the organic compounds from damaging the water quality. Protein skimmer designs have several variations, mostly centered on the way the tiny bubbles are generated.
Venturi protein skimmers use a property of fluid physics to generate very tiny bubbles ideal for protein skimming. The design is based around a type of valve called a venturi valve, with a pinched center. When a pump forces water through this valve, the changes in pressure generate almost microscopic air bubbles, which create the ideal foam for protein skimming. These bubbles rise through the body of the skimmer, producing foam that bubbles out into a collection container.
Other Types of Skimmers
The venturi skimmier is one of several types of skimmers. The oldest and cheapest is the airstone-based skimmer, which uses an aquarium airstone and an air pump to generate foam. In the aspirating pump, air is injected directly into the water pump, so the action of the pinwheel creates foam in the pump's motor itself. Downdraft skimmers spray water at a high speed into the body of the skimmer to generate foam.
Pros and Cons
Venturi protein skimmers have several advantages over other pumps. They generate the finest foam and don't require the replacement of an air stone. Additionally, venturi skimmers can be shorter, since their foam requires less transit time to pick up waste. Venturi skimmers require much less adjustment than other skimmers. Venturi skimmers have two related downsides: They cost more than regular pumps, and most models require a separate pump.