From The Aquarium Wiki
- A protein skimmer is a device for removing excess protein from the marine aquarium before it gets a chance to decay via the nitrogen cycle. In a salt water environment proteins will stick to the surface of a bubble. A protein skimmer introduces bubbles into a chamber for that protein to stick to. Generally there is a large cylindrical, or cone shaped column which the bubbles rise in. At the top of the column the bubbles converge into a foam that is collected and discarded. This discarded waste is commonly known as "skimmate."
What makes an effective skimmer
- A skimmer needs to be sized appropriately for your tank. This can be challenging due to the fact that most manufacturers will rate their skimmers based on a fish only load. For all intents and purposes when setting up a reef tank multiply the rating by 0.5, and if setting up a SPS only reef multiply that initial rating by 0.33 instead.
- The first thing to look for in a skimmer is its application. If a "hang-on" skimmer is needed then make sure it will fit behind the tank and that it is rated for the load that will be placed upon it. If in a sump make sure it will fit in the sump and that there will be at least 1/2" to remove the collection cup. If there is no room in the sump but still room under the stand then an external skimmer will be another option, just be careful in how you set these up as they can dump your tank water and skimmate on the floor.
- There are many things that will make a skimmer more effective than another, but there are two that seem to produce the best results. After that only marginal efficiency will be gained by design improvements. The first thing to look for are lots of bubbles, the finer the bubbles the better. Skimmers that have needle wheel and pin wheel pumps will produce some of the finest bubbles for their cost.
- Because the surface area of a sphere is not a linear relationship to the volume inside, the finer the bubbles the better the surface area. The second is contact time, contact time can be increased two ways. The first way is with a larger skimmer body. The second way to increase contact time is to choose a skimmer with a recirculating pump. By increasing the amount of time the air is in contact with the protein laden water the chances are higher that more waste will be collected. Other design improvements include cone shaped bodies, bubble plates, and gate valves.