The fish only aquarium or reef aquarium has a number of devices designed to help maintain the correct parameters, hopefully ensuring healthy livestock with a long life. These are heaters, water level controllers, calcium reactors, lighting controllers etc.
All of these devices service a particular area. For an obvious example, heaters maintain temperature. The action of these devices is appreciated by the aquarist as the action is usually obvious. There is one device though which sometimes causes doubt, and that is the protein skimmer.
Again and again it is said how important the quality of the seawater is, and how it is imperative that high quality is maintained. The protein skimmer is a device that acts directly on the seawater quality and should be present, particularly on the aquarium of an inexperienced aquarist.
The protein skimmer (let’s just call it a [tag-tec]skimmer[/tag-tec]) either hangs on the side or back of the aquarium, or is a standalone that sits alongside the sump. A pump, usually supplied, is sometimes within the skimmer body (hang-on) or is inside the sump (standalone). The pump sends water through the skimmer, and at the same time a venturi inlet (taking the venturi as an example) allows air to flow down and mix with the passing water. The pump impellor (there are various ways this is done) smashes the air into minute bubbles. These bubbles enter the skimmer chamber with the water.
As can be guessed, the skimmer removes ‘proteins’, or organic substances from the water. To rid the water of these organics an air/water interface is required. This interface is the bubble, or rather the many numbers of them in the chamber. Organic molecules are hydrophobic/hydrophilic. This simply means that part of the molecule repels water and some of it is water soluble. The molecules in the water react to the bubbles by their water repellent part attaching to a bubble. Many molecules can attach to a single bubble.
A good skimmer will have a chamber that appears white because of the very high number of bubbles in it. These bubbles should be very small. The skimmer should be rated for around twice the net capacity of the aquarium system. If the skimmer is working correctly, a dirty looking foam should rise up the neck of the skimmer and be collected in the cup, where the bubbles burst into a dark liquid. (Skimmers do not always collect much for a few days after they are new, or after they have been cleaned, or where a low amount of organics is present in the water.) This skimmate should be emptied from the cup regularly and the cup and neck kept clean. The scum deposits in the neck etc will reduce efficiency.
A large build up of organics in the seawater can result in problems for the livestock – in very bad examples even death.
Some more advanced aquarists actually have their skimmers on timers as they do not want them to run full time. This is to do with certain corals being able to use organics as a food source. This practice should not be undertaken by a novice aquarist, as it requires careful monitoring.
Some aquarists run what is called ’magic mud’ systems. This simply means that a special kind of ’mud’ bed is in the sump, and it is claimed that because of this a skimmer is not required. Some aquarists may well be skimmerless, but many others run a skimmer anyway as they feel insecure without one.
Is there a drawback to using a skimmer? Yes, there is. The removed substances will include trace elements, and these trace elements are required in the seawater. However, regular routine water changes, and even trace element dosing if thought necessary, will maintain the element presence.
A properly sized and maintained skimmer is invaluable. It is arguably the biggest asset, or at least one of them, to the aquarist in the search for high water quality.