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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.
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