How Air Stone Skimmers Work

Air stone skimmers are important parts of saltwater aquariums because they provide oxygen and a clean environment for the aquariums' organisms. Each air stone skimmer is composed of a cylinder, water pump and wooden air block. It functions by injecting air bubbles into the aquarium water.

  1. Purpose

    • Air stone skimmers are a type of protein skimmer. The main purpose of a protein skimmer is to get rid of dissolved organic matter in aquarium water before it decays. Fish, bacteria and some algae that live in aquariums create organic waste and dissolved organic carbons as part of their natural metabolic processes. Dissolved organic carbons include enzymes, hormones, amino acids, carbohydrates and fats. If organic matter is left in the water, it breaks down into nitrite, nitrates and ammonia, which are detrimental to the aquarium's marine life. A protein skimmer also oxygenates the water, making the aquarium more habitable for its marine life.

    Skimming Process

    • Skimming removes suspended and dissolved waste from water through the injection or air bubbles. It relies on the chemical coagulation process. Organic molecules are non-polar at one end and polar at the other en. The polar end is attracted to water molecules, and the non-polar end becomes not attracted to water when it contacts air. Because of these characteristics, organic molecules become concentrated in places where air and water contact each other. The skimmer injects air bubbles in the water, the bubbles rise to the top of the water while taking dissolved organic molecules with them and the organic material becomes concentrated in a foam at the top of the aquarium. The skimmer removes, or skims off, the foam.

    Operation

    • Each air stone skimmer has a clear plastic cylinder that is about 4 to 6 inches in diameter and 24 to 38 inches tall. A water pump directs water into the cylinder. A wooden air block, also known as an air stone, is at the cylinder's bottom. The water is pumped into the cylinder's top and swirls in the column while small air bubbles from the wooden air block rise to the top. The foam that builds at the top of the column overflows into a collection cup that must be emptied periodically.

    Proper and Improper Function

    • Protein skimmers are used for saltwater aquariums and are not normally used for freshwater aquariums. The foam created by a properly working air stone skimmer is a ginger ale or beige color. The skimmer should be adjusted if it produces dark foam. A skimmer that injects too much air creates more foam than usual. Too little air injected into the water by the skimmer creates dry foam. The accumulated foam at the top should be thick so that it can be collected in the collection cup.