This is the third and last part of my discussion and description of my reef
tank. It focuses on filtration. As most of you already know, there are three
types of filtration: particle, chemical, biological. Because we have such
an enormous concentration of living organisms in a very small body of water
when compared to the ocean efficient filtration is virtually a necessity.
One caveat, it is possible to have a reef tank with very little filtration
if one is content to have no or very few fish, and those require very little
feeding. In fact, when reef tanks where just making their appearance in the
early eighties it was gospel that to have a reef tank one could have very
few fish. Today, however, most of want a significant population of fish,
but have to utilize efficient filtration techniques to make it work.
The bottom line is the same; one must achieve a balance between the producers
of waste and the consumers of waste. If the producers, fish for example,
produce more waste than the consumers can eliminate the reef tank will soon
resemble a eutrophic lagoon choked with undesirable algae, especially slime
algae. At this point I should note that it is always necessary to have an
active clean up crew of snails, crabs, cucumbers, etc. because it is not
possible, even with the best husbandry, to keep all algae out of one's reef
tank.
It is relatively easy to maintain a pristine reef tank environment with
a minimum amount of producers like fish. However, myself like most contemporary
reef keepers want fish in their man made reef, and because reef fish are
usually very healthy in a reef tank when compared with a fish only tank they
survive and grow. As they grow they require more food, and consequently produce
more waste. This puts more demand on the consumers, and if the demand is
not met the general health of the reef will slowly decline. My clown triggerfish
pictured here has tripled in length and I'm sure weighs 4 to five times as
much as when added to my reef, and this in less than 2 years.
Though it is true that photosynthetic corals (soft or hard) will consume
some waste as their zooxanthellae photosynthesize in the presence of light,
the amount of waste consumed by them is very small. As a result, most reef
keepers utilize a variety of filtration devices to consume waste, and also
replace significant amounts of water at fixed intervals with nutrient free
artificial sea water.
I have a lot of fish, some of whom over the last 20 years or so have grown
quite large. They produce a lot of waste, and this is what I do to eliminate
as much of it as I can. I can assure you that it's an uphill battle. Aside
from a canister filter most of my 10-foot tank's filtration takes place in
a 300-gallon Rubbermaid vat. The vat is convenient because it has great surface
area at only 18-inches in depth. This allows me to sit a 50-gallon refugium
in it on plastic milk crates. Also on milk crates is a 60-inch ETS down draft
skimmer that is driven by an Iwaki 70-RLT.
Canister filter:
The canister filter is changed every two weeks. It is filled with ESV activated
carbon and Two Little Fishies' PhosBan. These two products are used essentially
for chemical filtration: the carbon keeps the water clear absorbing discoloring
organics, while the PhosBan reduces orthophosphate to levels that are hard
to measure.
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ETS Skimmer:
This powerful skimmer removes a lot of particulate matter, but more importantly
functions as a micro-alga filter. Its skim mate is composed largely of phytoplankton.
These small algae photosynthesize thereby removing nutrients (waste) as they
are harvested from the system via the skimmer.
Refugium:
From the refugium I harvest, about every two weeks, a 5-gallon bucket full
of Caulerpa sp.
By exporting the macro-alga whatever nutrients it absorbed to grow is removed
from the system.
Despite all of this, nutrients, especially nitrates accumulate in the system
necessitating a 30% water change every couple of months, with newly prepared
artificial seawater. The freshwater is first prepared from RO/DI filtration.
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