Foam on the top of your tank? We may be able to help.
What is protein skimming?
Protein skimming or foam fractionation is simply mixing small air bubbles in water to remove dissolved organic compounds (DOC) and particulate matter from the water. Dissolved organics are attracted to an air/water interface, hence the oil slick on the surface of the water in a tank without an overflow. When the small bubbles are mixed with the water the DOC is attracted to the surface of the bubble, giving the bubble surface tension. The bubble rises in the skimmer, bumping into other bubbles, forming larger bubble and bursting at the top. The rising bubbles that eventually rise into the collection cup of the skimmer form larger bubbles. The foam created in the cup breaks down into a dark smelly liquid, that you will not believe came out of your tank. Have you ever been to the beach on a windy day? If so you have seen the white caps on top of the waves. That is nature’s protein skimmer. The foam on the waves washes onto the beach, remember the smell? The effluent caught in the collection cup of our skimmers has a very similar smell.
The necessity of protein skimming is a subject for debate. If you do not employ a protein skimmer, you must have some other way to export DOC; whether it is granular activated carbon (GAC), water changes or some other method. There are pros and cons to protein skimming. In my opinion the pros out weigh the cons and therefore I use protein skimmers on my systems at home.
Lets take a look at the pros first:
1) Removes DOC
2) Prevents nitrate buildup in the tank
3) Increases redox
4) Increases gas exchange
5) Lowers bio-load, by removing particulate matter before it can be mineralized
6) Stabilizes ph
7) Provides export for ortho-phosphates
Cool Helps prevent undesirable algae, by removing it’s nutrients
9) Gives the water a sharp crystal clear look
Now the cons:
1) Removes trace elements
2) Removes beneficial plankton
3) Relatively expensive
4) Can lower specific gravity (over time) by removing small amounts of salt from the water via splash
As I have already stated skimmers are not a necessity, all of the pros can be accomplished through other means. As far as the cons, all can be overcome by trace element supplementation, water changes and some skimmers are becoming very reasonably priced. The amount of plankton removed by a skimmer is negligible, with the exception of large hang-on models.
Now back to the original question; is it right for you? I recommend protein skimmers for all reef hobbyists, as you become more experienced and understand the dynamics of your system; you will have a better knowledge base to determine if you need one. Until then, a protein skimmer may just be the difference between success and failure. Protein skimmers literally give you room for error. Most new aquarists and some more experienced aquarists tend to over feed their fish. Skimmers can help avoid problems from this practice by removing the uneaten food before it is added to the bio-load. As with any piece of equipment for your aquarium you have to weigh the benefits versus the cost and decide whether the expense is worth it to you, but in my opinion skimmers are an invaluable resource for our aquariums. Adding a skimmer to your aquarium will give you a healthier more beautiful aquarium, and that is what we’re after anyway, isn’t it?
Should you have any questions or comments about this article please feel free to post in the Saltwater & Reef – General Discussion forum.Filed under Articles, Saltwater.