Quote: Eric Borneman : " Skimmers are good at removing hydrophobic organic compounds, but are the organics really the reason that a tank would crash or things fail to thrive, and how effective are they at removing truly detrimental compounds, whatever they might be, and to what extent do they vary between tanks and in what amounts do they occur? We call them protein skimmers, but how much dissolved protein is there in water, is it detrimental, and if so, why do people add amino acid supplements to their tanks?
What I am most concerned with as detrimental to tanks are refractory organics that yellow the water and secondary metabolites that are toxic. Both ozone and carbon can take care of these as well as other absorbent materials. I didn't find skimmers to be very good at adding oxygen to the water. Now, if you have just added a bunch of new sand or something spawns or something is accidentally added to the tank....I think it is good to have all guns blazing, including a highly efficient skimmer. But, the funny thing is that the success of growing corals came almost hand in hand with better lighting, strong water flow and live rock....no one ever teased out any data as to which was the factor, or if all of them were. Clearly, they are not needed to have a succesful reef tank, nor is really strong lighting. The lighting is species specific, and I suspect the skimmer might be the same. A soft coral and sponge dominated tank might have more use for a skimmer than a stony coral dominated tank. Tanks with large nutrient inputs might have more use for export, although export can come in a number of flavors. " End Quote.
How does a skimmer actualy work?
" Protein skimming, also known as "foam fractionation", has its roots well established in industrial applications. It has been employed in waste treatment since the 1890's to separate various metals, proteins and surfactants from solution and has been used in marine aquarium keeping at least since the 1960's. How does it work? Simply stated, a protein skimmer mixes tiny air bubbles (consistently produced and sized) with water in a contact chamber in an effort to separate dissolved organics from the main body of water. This separation of organics is achieved by the polar properties of dissolved organic molecules and their attraction to the "charged" air-water interface of fine bubbles. These large, polar protein molecules have a positive and negative end and when they come into contact with small bubbles, they end up coating the surface, much like soap does. It is interesting to note that the same forces that attract these compounds to the air bubbles in your skimmer also attract such elements to the air-water interface at the surface of the aquarium, hence the need for very efficient collection of surface-skimmed water to feed your protein skimmer.
Dissolved organics are channeled inside the contact chamber of the protein skimmer with foam and bubbles where they migrate upwards into a collection cup. This is the crux of protein skimming. It is the only means of filtration that actually exports organics entirely from the water. Other means of physical, chemical, and vegetable filtration merely breakdown or absorb/adsorb compounds, but they still allow such elements (proteins, scatols, phenols, metals, etc.) to remain in the water column. They are just in a different form or location, like plant or algae tissue, by having been taken up as nutrients. Here, they can easily be imparted as degraded byproducts or contaminants wholly back into the aquarium system. Skimmate, however, is completely exported and isolated from the system water. "
While it is possible to maintain a reef aquarium without a skimmer, I would still recommend their use for reef systems, only because most reef system's bioloads are such that the natural biological diversity and balance are not capable of dealing with the day to day input of nutrients, and a skimmer seems to help reduce what the life within our aquariums produce by their just being alive and being fed. Believe it not, but even after decades of their being available, no one really knows exactly what a skimmer removes from the water. Hopefully we will gain that knowledge soon.
One point of discussion that I would like to raise is the actual need to use a skimmer. My thoughts on this subject deals with a given aquarium's biological diversity and the time that it takes to allow a system to achieve a balanced maturity. In that, when we first start up a reef system, it can in no way deal with the flood of life and food that we throw at it right away, and the use of a skimmer allows us to get away with what we normally do, and that is to stock our aquariums to fill them with fish and corals within the first six months of start up. I believe if one were to change the typical stocking habits to take into account nature's nutrient food chain, you would see that we tend to stock an aquarium backwards and are forced to use skimmers to correct that mistake. Once the skimmer is in use, I do not think anyone ever gives thought to the possibility that after a few years, the system may be able to get along just fine without the skimmer. Once the habit of running a skimmer is in place, odds are that the skimmer will forever be in place. I can think of two methods that would allow either not ever having to purchase a skimmer or being able to remove one that is already in place.Natural Food Chain - As I mentioned, with a typical start up routine, we pretty much go against what nature itself could be doing for us. If we can get in the habit of looking at our aquariums as a food chain and an ecosystem that is starting out from scratch, along with the realization that natural ecosystems do not happen over night or within six months, we can then stock our aquariums from the bottom of the food (nutrients) ladder and work the system upwards while giving the needed time for each step of the ladder to mature, grow and become balanced with the addition of each new "step". I have found that for a balance to be achieved, giving two years towards that goal would be fairly typical. Here is how I feel a reef aquarium could be created with alot less trouble as well as allowing it to do all of the work that skimmers and other pieces of equipment do in its place.
1. Realize first that you are not going to get an instant reef and look upon it as a long term goal / procedure.
2. At start up, stock the tank with its initial base rock and base sand and get past the initial cycle. Once there, then stock the tank with live rock and live sand along with all the life that comes in with live rock /sand. Add a sea cucumber and a herbivore snail clean up crew. Allow the tank six months to run as is. This will allow all the life that forms the basis of the food chain to get established.
3. After six months, start adding some corals and do so over the course of the next six months until your aquarium is stocked with what coral species you wish to keep. Once you start having to feed the corals, that food input will also feed the first occupants, which was the bio filter and all the small life forms that make up the bulk of the unseen , or rarely seen life that consumes, recycles additional nutrients. Allow the system an additional six months to find its balance with what is within the aquarium now.
4. Now that the aquarium is a year or more old, now we can add the top of the food ladder, which are fish. I would start out with just one fish and space out any further fish additions at least 3 to 4 months apart. This will give the bottom rungs of the ladder the time they need to grow, reproduce and catch up to form a balance once again.
By the end of two years, you should have a very balanced and almost self sustaining ecosystem, without having to buy a variety of life support equipment such as skimmers, reactors and all the other gizmos that keep our aquariums laying in bed hooked up to machines to remain alive. I think its high time this hobby learns to pull the plug. Buck the System - A typical start up and stocking involves just that, bucking and ignoring the entire nutrient chain/ladder. Where we fill the tank as soon as possible with all the top rungs of the ladder and have to employ skimmers, reactors and all the other mechanical devices that do the job of the lower rungs of the nutrient ladder. Sadly, once we have our aquarium "plugged in", it remains plugged in. And must remain so since all of that equipment suppresses all the life that forms the basis of the nutrient cycle by just simply starving them into low densities and keeps them there. After two years, there is no reason why we can not start unplugging the aquarium and if done slowly, you will probably be very pleasantly surprised to see the system respond favorably with the added benefit of having a much more diverse aquarium with all the little life that does the bulk of maintaining balance with the added benefit of all that little life reproducing and feeding the upper rungs of the ladder. All the lower rungs need is to be fed (what the equipment is "eating") and given the time to respond / reproduce. In the end, you will have an aquarium that is almost maintenance free, much more of an actual reef, and you will be able to sell all that life support to the next hobbyist who can not find the patience or the nerve to allow nature to takes its course. I have learned and accomplished this feat simply because of where I live there is not any equipment available to me and have been forced kicking and screaming into allowing my aquarium to become "natural". And no, this is far from being a new idea, I am sure any one that has been in the hobby longer than a few years remembers the "Berlin System" as being the new next method of reef keeping. To me it seems that the hobby in general has never fully embraced that concept and remains addicted to life support. Is this for everyone? No, it never will be, just as there are diverse methods, there is the same diversity of people with different goals they want to achieve or accept. If your idea of a reef is having some blue tipped acropora sitting on top of some dead base rock, then equipment is a must, or if you wish to maintain high numbers of the top of the chain, a balance will never happen and is where equipment must step in. But if you wish to have an aquarium that mimics a natural reef, then you have no choice but to let it be natural and stock it as such.