Aquarium Protein Skimmers are one of the most important devices you can use to maintain water quality in a saltwater aquarium. Protein skimming removes organic pollutants before they break down into nitrates and phosphates. The improved water quality is beneficial to fish and corals and may reduce the frequency in which water changes are necessary.
Aquarium Protein Skimmers are available in a few different styles: units that sit in a sump, units that sit outside of a sump and those which hang on the back or rim of the aquarium.
Some of the most popular brands among marine and reef aquarium hobbyists include ProClear Aquatics, Coralife, Marineland and Red Sea.
A protein skimmer basically works by injecting air along an water column.
This process utilizes the unique properties of saltwater, including the ionic components that result in hydrophilic (water loving) and hydrophobic (water hating) compounds in saltwater. Independently of the type of skimmer is used, and there are at least five different designs available, they all work by producing air bubbles and having the water from the tank come into contact with these bubbles. When these bubbles come into contact with saltwater, electrochemical factors come into play that cause surface active compounds to adhere to these bubbles and be removed in the foam. The smaller the bubbles the more contact area will be and more compound extraction occur. These compounds not only include proteins and amino acids but also include molecules containing copper, magnesium, calcium and manganese as well as detritus, phenols, and microalgae. Protein skimming is indiscriminate in what it removes, it can also remove good compound like micronutrients. Therefore when adequate skimming is employed trace elements may need to be added either through water changes or trace element supplementation. The skimmer might over foam when you add micronutrients like iodine or strontium, in that case you can turn it of for some time (couple of hours to a day).
Regardless of which protein skimmer is chosen, several factors should be taken into account, with cost being the least of them. First select a skimmer that is recommended for your size of tank or slightly larger. It is better to overskim a tank than to underskim it. Secondly, make sure that the skimmer is easy to clean and maintain. The easier this is to do, the more likely it is to get done. Thirdly, do regular maintenance on your skimmer. A skimmer only functions properly when it is well maintained. Cost should not the deciding factor because in most instances the best skimmers generally cost a little more, but the dividends of having an efficient, easy-to-clean skimmer pay for itself in the long run.