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re: BGA-What is the BESTS way to treat

Al wrote:

"Fair enough, but just what are the features or conditions that lead to
bga ploliferation? In my admittedly limited experience, it seems that this
is the problem...  maybe there is more to bga proliferation than just
nutrient excess or water circultion.... just a thought, could be wrong,
again my experience is limited.  Al"

In reply to my letter regarding Robert Sirota's question:

> > What is the best treatment--erythromycin, H202, or potassium
> > permanganate--and why?
> The BEST treatment is to change the features of your tank that allow the
> BGA to flourish.  That requires an understanding of the dynamics in your
> tank, but once you have it, the solutions are simple and reproduceable.


I agree that there's more to the proliferation of BGA than just nutrient
excess or water circulation.  I don't want you to miss my point here;
whatever the cause is, it's likely to be part of the unique dynamics in
your tank, which only you can observe, understand and control. I can only
tell you about how it works in my tanks, and that may or may not have
anything to do with the way it works in your tanks.

We've discussed BGA on this list ad nauseum.  You could probably spend
days finding and reading all the archived content on the subject.  And
really, you should make an effort to read some of it.  I've described my
opinion and approach several times.  It changes a bit from time to time,
so I'll give it yet again.

Blue green algaes in general are essentially ubiquitous in nature, but
dominate over algae and higher plants only under environmental extremes --
high or low temperatures, high or low nutrient levels and so on.  Blue
green algae seems to behave similarly in my tanks. I could probably find
blue green algae in any of my aquaria at any time, but in open, well lit
areas where plants grow well the blue green algae is never visible.  There
are niches in the tank -- below the gravel line against the glass is a
good example -- where nothing else grows and where blue green algae are
not only present, but common.

When we find slime coating of blue green algae in our tanks these are
probably not just globs of blue green algae, but communities of
microorganisms in which the blue green algae is the dominant primary
producer.  I've never studied the slimes under a microscope; it's just my
educated guess that these "slimes" are in fact communities.  Like other
communities of organisms, the slimes are somewhat independant because they
can use multiple nutrient sources and cycle nutrients within the
community. Also like other communities they get more stable as their
biomass increases.  As a result, once the biomass is large enough to make
the community a nuisance, the community tends to resist simple methods to
remove it.

I never see blue green algae suddenly appear in my tanks and grow from
nothing to a nuisance in hours or days.  Their proliferation is always a
fairly slow process.  Usually when I first notice the slime it's in one of
those areas where nothing else grows -- like in a dark corner of the tank,
or against the glass, below the gravel line.  Over a period of weeks the
slime will gradually spread out from that original location.  Usually
those are shaded areas without good circulation.  The gradual spread goes
on for weeks or months.  After a while the slime spreads into more open
areas and then it becomes a problem.  Also by then the community is large
enough that you can't get rid of it just by removing the readily obvious
slime.  It grows back.  Quickly.

I control blue green algae mostly by changing conditions in those niches
where it hides and from where it spreads.  In the case of stuff growing
below the gravel line I have taped the outside of the glass below the
water line to keep light out.  In most other cases I find my best solution
by taking a positive approach -- by asking myself how to best improve
conditions for the plants, not by looking for new and different ways to
kill the blue green algae.

If the blue green algae has spread much beyond it's starting point then
it's necessary to first remove as much of the slime as possible and to
look for ways to improve growing conditions more generally.  For instance,
in the past I have removed dense and unhealthy stands of carpet plants so
that old growth can be replaced by healthy young growth; I've thinned
stands of plants that block circulation or shade themselves and smaller
plants; I've replaced weak lighting; I've moved plants that have grown
against the glass; I've even increased fertilizer additions.

In any case, I find it necessary to change something, not to just clean
things up and continue with the status quo.

The method varies from case to case because the dynamics of each tank are
different.  It would do no good, for instance, to increase the lighting on
a tank where the light is already brighter than the plants need or to
increase fertilizer in a tank where the plant growth is limited by low
light or low CO2.

For example... I have an old tank that I keep around to show me where I
came from in this hobby.  It gets no added CO2, very little fertilizer and
it's lighting is dim at best.  It grows java fern and three different
kinds of crypts and it's populated with loaches, clown plecos and false
SAEs.  BGA appeared at the gravel line at the front of the tank more than
a year ago and since then has gradually spread, first along the corners of
the tank and then out onto the plants growing against the glass.  Some
time soon I'll fix the problem by giving the tank a good cleaning,
replacing the old lights, fertilizing the plants and maybe taping off the
exposed sides of the substrate.  That should take care of the problem
forever, or at least until the new lights get dim and I stop fertilizing
again for a few years.  And if by some odd chance that doesn't work then I
can move plants away from the edges of the tank where they harbor the blue
green algae and replace the over-the-back filter with a circulating power
head to get better flow or I could even start adding CO2.  There's always
another option.

Experience is real helpful when it comes to controlling blue green algae
without poisons, but you will never get that experience if you keep using
chemical controls.  Over the course of 10 years or so I used copper
sulfate, penicillin and erythromycin to killl blue green algae but I found
that afterwords I knew nothing more about the problem then I did at its'
onset.  Nothing changed, so the problems ultimately repeated themselves.
When I swore off chemical controls I started learning, and each time I
solved a new problem I found I understood more and more.  Now it isn't a
problem because I always have a solution.

Roger Miller