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re: A different kind of algae

I'm sorry it took so long to reply to this post, but I've spent the last
few days catching up from about 30 APD mailings behind.

>From: Destard at aol_com
>Date: Sat, 22 Mar 1997 22:56:20 -0500 (EST)
>Subject: A different kind of algae
>     I set up a fifty-five gallon aquarium roughly 6 months ago, and it
>been flourishing for the majority of that time.  However, recently it has
>developed incredible algae growth all over the leaves and the sides of the
>aquarium.  This algae is a type which I have never encountered before.  It
>forms in very thick, slimy sheets, and comes off very easily.  The real
>problem with it is that it grows at unheard-of rates and totally cuts of
>light to my plants.  It advances easily at the rate of two to four inches
>day.  My aquarium also developed an unusually strong odor along with the
>algae breakout.  I normally associate a strong odor with blue-green
>algae/bacteria, but this algae seems to be very different from blue-green

Mmmmm.  It looks like, smells like, acts like, and quacks like
cyanobacteria.  That's my bet as to what it is.
>     Before the algae breakout, my tank was filtered by a Fluval 203 with
>ceramic pre-filter rings and foam, plus a Whisper 3 for mechanical
>filtration.  I "injected" yeast-produced CO2 via a upturned soda bottle.
> Give or take a week, at the time I first noticed the algae breakout was
>the time when I replaced the Fluval with a trickle filter.  This caused my
>to promptly shoot up to about 7.6 from 6.8.  (note--I experience
>ph swings from day to night, as the ph goes from 7.68 or so at the highest
>point and 7.24 or so at the lowest point, as measured by the Pinpoint ph
>Monitor.)  I then started to inject CO2 with a diy reactor, in which water
>pumped through a 2" wide reaction chamber filled with Fluval ceramic
>pre-filter rings.  I am not sure how efficient or inefficient this reactor

Your large pH swings lead me to believe that you may have very low
alkalinity (KH) in your tank water.  This may not be true, but that's what
it looks like.  I've been able to eliminate cyanobacteria infestations
without antibiotics by increasing the available nitrogen in the water,
increasing the calcium and magnesium levels in my water, attempting to keep
the phosphorus levels in my water very low, and removing the stuff
manually.  I unintentionally wound up with extremely high nitrate levels
while doing this, so be aware that my methods are not guaranteed to work.

I believe the increased calcium and magnesium levels in my water may have
had a primary effect on the health of my snails, which experienced a
population explosion and quickly began to consume the cyanobacteria coating
inside my tank.  They may have also had a negative effect on the
cyanobacteria itself, but I can only speculate in that area.

I believe the increased ammonium/nitrate in my tank, plus potassium
assisted the plants in their ability to absorb phosphate and other
nutrients from the water, helping the cyanobacteria to starve, perhaps.

I added phosphate absorption media to the settling tank where water would
flow through it.

Finally, despite what appears to be a tendency to develop an allergic
reaction and throat infection any time I deal with the stuff, I manually
plucked cyanobacteria from the tank, removing it and the nutrients it
sequestered from my system.

A number of people suggested to me then and will suggest now that you use
erythromyacin to kill the cyanobacteria, if that is indeed what you have.
I have absolutely no problem at all with this suggestion, and it will
definitely be a good choice if you don't have the months at your disposal
that it took me to rid my tank of the problem.  I would suggest frequent,
large water changes after the treatment is complete to ensure that you
remove the nutrients this growth needs from your water.

David W. Webb in sunny, green Plano TX.