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RE: Algae and Snails



As usual, every new issue of the APD contains plaintive cries from someone
fighting either algae outbreaks or snail overpopulation. On the latter, I
have to agree with Olga and Tom Barr - loaches can and will provide a
control on snail numbers. Plus, they are great fish with plenty of
"character" and there are numerous species to choose from. Just don't keep
them singly - they are schooling fish and do best in groups. Kept alone,
they have a tendancy to either do poorly or get agressive.

I know that its bad form to quote a person without first asking permission,
but I came across some comments by Craig Bingham, the chemist who writes for
Aquarium Frontiers, which are (IMHO) quite appropriate for people here, even
though he wrote it with marine tanks in mind. Craig used to be a member of
the APD (he was one of the people in the middle of the "what color is water
in a white bucket" debate).

"Diatoms are interesting in that they are the major group of algae that have
an absolute requirement for silicate. But we all know it takes nitrogen,
phosphorus and other essential micronutrients to grow hair algae and other
unsightly types of algae in a reef aquarium. [in ANY aquarium, not just a
Reef tank] Diatoms have the same requirements, with the additional, absolute
requirement for silicon for growth. So, it takes more than just silicate to
grow diatoms, and if diatoms are growing, they are growing by using
nutrients that might otherwise fuel the growth of other types of algae.
Unfortunately, this is completely lost in the popular aquarium literature."

"Moreover, diatoms are very easily controlled by herbivores. Most of the
herbivorous snails sold in the aquarium trade are primarily diatom
predators. By limiting silicate input into an aquarium without similar
attention to other nutrients, you arenít just selecting against diatoms. You
are selecting for other types of algae, some of which may be considerably
more difficult to control biologically than diatoms. If I had to pick one
type of nuisance algae in my aquarium, Iíd pick diatoms every time."

"If I were to tell you that there is an organism that can help compete with
nuisance algae for nutrients, and will allow you to feed your system
phytoplankton simply for the cost of rubbing a magnet on the front glass of
your tank, you might be willing to pay quite a lot of money to get such a
creature established in your system. Because this organism actively reduces
nitrates and packages nutrients in easily skimmable (as well as nutritious)
packages, you might be willing to pay even more. Iím hopeful you will not be
too disappointed to learn that you already have them in your aquarium, nor
too sheepish to learn that you have been doing your damnedest to wipe them
out. They are none other than your old enemy, diatoms. One sometimes wonders
if the minor aquarium gods always know what they are doing, or what
implications their choices might have for their aquatic worlds."
********

Now, Diatoms are usually only noticed in great numbers early on in a tank's
life - as a brown coating on the glass, but he makes an interesting point
about them acting as competitors with green algae for nutrients in the water
column and the fact that herbivores can easily consume the diatoms. (i.e. it
is easier to find something that will eat the Diatoms than it is to find
something to consume nuisance algae.)

Very little has been written about the use of freshwater microfauna (i.e.
small aquatic bugs and other organisms) in frehwater tanks, but I would
imagine that they too would act as a brake on diatom outbreaks but I'm sure
there could be a balance point found where the populations of the various
diatoms, algae species and herbivores keep one another in check and allow
the higher plants to take their role center stage.

Food for thought, perhaps.... except, of course, for the "bleach
brigade".... <g>

James Purchase
Toronto