There are various items of equipment that assist the aquarist, the items differing depending on whether the system is fish only or reef. For example, the reef system, particularly if it is quite large and contains hard corals, could use a calcium reactor – it would be unusual for one to be used on a fish only system.
There are items of equipment that are common to both systems, and an obvious example is heating, normally combined heater/thermostats. Another item that is common to both is the protein skimmer.
The protein skimmer is probably the best equipment aid to seawater quality that the aquarist owns. It therefore makes good sense to take a little care in choosing it.
Protein skimmers use a pump to pass seawater through a chamber where it is exposed to an air/water interface. This interface is created in the majority of skimmers by the use of a venturi valve. Put simply, an air inlet of a particular size is positioned just before the pump impellor. As the pump moves the seawater air is sucked in through the inlet. The air and seawater pass through the impellor where the air is thrashed into tiny bubbles, huge numbers of them. There are variations on this impellor/seawater/air theme but the principle remains the same.
When considering the purchase of a protein skimmer, the first piece of knowledge that the aquarist requires is the net gallonage of the system, which means that the gallonage of the display aquarium and any sump in use should be combined. It is not necessary for this gallonage figure to be accurate, but should be a reasonable approximation if the true figure is not known. Remember it is the net gallonage, that is the seawater amount after displacement by rocks and sand.
The net gallonage of the system is required so that the protein skimmer can be adequately sized. Manufacturer’s quote the amount of seawater that a particular protein skimmer can cope with, and sometimes these quotes are ambitious. The usual method is to obtain a skimmer that is quoted as capable of dealing with twice the seawater that the aquarist actually has. Having said that, of late some manufacturers have been more realistic with their quotes, offering a range of skimmers. Nevertheless, purchase the chosen unit on the plus side, that is, obtain one that is quoted above the known seawater amount.
So which protein skimmer should be obtained? There are two types that mainly interest the aquarist, and these are the ‘hang-on’ and ’stand-alone.’ The descriptions are generally self explanatory – the ‘hang-on’ type is useful for aquarists who wish to place it on the display aquarium but wish to minimise the sight of it within the aquarium, and the ‘stand-alone’ is usually used alongside a sump. Some models are adaptable to both types. Skimmers are supplied with pumps adequate for their purpose.
Having decided the type, the aquarist now needs to pick a model. As with most things, some are better than others.
The skimmer should be properly designed and if skimmers can be seen running then a general simple check will indicate that this is so. The first thing to look at is the bubble generation. Skimmers have a bubble chamber, and this chamber should be a milky white colour, or somewhere near it, and packed with bubbles. The bubbles themselves should be very small. Also listen to the noise of the unit – if it is going into the lounge for example the noise needs to be very low.
Also examine the skimmer and be sure that it is serviceable bearing in mind the location it will be in. For example, during a cleaning exercise the cup needs to be removed from the unit, and this means lifting it upwards. If in a sump, is there room?
When the aquarist cannot see a skimmer operating, then it is best to note down the names of a few types that appear to be suitable. Using the internet, have a look at any reviews that could be available, and note the comments made. Also make enquiries on forums, so that other aquarists who have experience of the skimmer can make a comment. A visit to the manufacturer’s website could also be made, to obtain the specifications of the model(s) of interest.
As already said a protein skimmer is important, and it is very worthwhile giving time for research and checking the performance, as far as possible, of any particular model.
There are other types of skimmer in addition to the venturi models, such as air driven and down-draught types. The venturi skimmers are the most used.
To round off, why is a protein skimmer important? It has already been stated that they are a tremendous aid to seawater quality. This is because a protein skimmer removes dissolved organic matter (DOM). The seawater passing through the bubble chamber will usually be loaded with DOM (the load varies because of circumstances). DOM molecules both repel water (hydrophobic) and are water soluble (hydrophilic). When they are in very close proximity to air, as they are in the bubble chamber, the water repellent part attaches to a bubble. Many molecules can attach to a single bubble in this way.
As the bubbles slowly ascend in the bubble chamber, the DOM molecules go with them. At the top, the foam created because of the attached molecules is stiff, and rises up the neck of the skimmer, and then falls into the collection cup, where periodically it can be removed. Therefore the seawater quality is optimised.
It is important that a protein skimmer is regularly cleaned (the neck and cup) or the efficiency of the unit will be reduced.
The downside of a protein skimmer is that it will not only remove DOM but will also remove trace elements that are better left in the seawater. However, because of the great value of the skimmer this is disregarded. If the aquarist does routine seawater changes then the new seawater will introduce trace elements.
When the dark and smelly effluent that collects in the skimmer cup has been seen, it becomes obvious why they are such an asset.