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Re: Algae problems and Oxygen diffusion in roots

>Jon Wilson wrote, May 20:


>Substrate has been thoroughly clean a couple times a month. It still looks
>great. Actually, other than the back glass, the tank still looks fine, for a
>basically empty tank. The water is very clear, even when viewed through 6
>feet of it.

If all you have is green algae that can be wiped off easily, plus a little
green spot algae, then pond or ramshorn snails can take care of it for you,
provided you don't want to keep big fish in that tank that eat snails.  I
know that a lot of people want to get rid of ramshorn or pond snails, but
for me they are essential in keeping soft, attached algae under control,
and they only rarely do any damage to my plants.  Actually, pond snails are
incapable of doing any damage to plants, and may be even better at cleaning
up soft attached types of algae because they multiply so quickly when well
fed.  Pond snails can't make any impression on green spot algae, but the
ramshorns keep it fairly well controlled.  I have found that these two
kinds of snails can clear up cyanobacteria (bluegreen algae), but they do
it only very slowly if the algae is well lit.  If I turn off the lights, so
that the tank is only getting room light (and is not near a window), the
snails really go to work on cyanobacteria in a hurry.  I suspect that in
dim light the cyanobacteria is unable to make definsive chemicals that
discourage consumption by snails.  In other words, after a couple days of
darkness or dim light, the cyanobacteria becomes really tasty nutritious
food for the snails.  Occasionally, one of my little windowsill cultures in
gallon pickle jars gets taken over by cyanobacteria, and when I look at it,
the snails have either all died off, or there are only one or two little
ones left. I have found that I can take the jar from the windowsill to the
back of the room and, after a couple of days the snails begin to prosper
and feed on the algae.  Pond snails can multiply explosively and clear up
even thick accumulations of cyanobacteria in a week or two.  Ramshorns are
a lot slower in reproducing, and can take a month or two to multiply up to
the point where they have cleaned everything up.  In any case, my plants
have always survived the period of dim light, and start growing again very
nicely when returned to the windowsill.  I think, in all cases I can think
of, the bluegreens have never come back, not even after two or three years.

Wesley Dean wrote May 20 re filament algae

>I have a heavily planted tank that is suffering from a greenish-greyish
>filament algae.  I have noticed that my Platys pick at it a bit, but not
>enough to really make an impact.  I understand that if I cut back on feeding
>them they will probably make a larger dent, but I'm worried about my other
>fish.  Will Tetras or Gouramis find other things to nibble on if I cut out
>the flake food.
I think that tetras and gouramis are entirely carnivorous and not
interested in grazing on algae, even if starved.  Guppies, platties and
swordtails are omnivorous and mollies like algae even more that the first
three.  If your filamentous algae is tough and hard to the touch, rather
than soft and mushy, snails wont be able to eat it, and you may have to get
SAE's or resort to the complete 5% bleach treatment.  Large tadpoles can
eat algae pretty well, but some of the hair algae, such as Cladophora and
Oedogonium are too tough even for them.  Scuds (Gammarus) eat hair algae
well, but they then eat your plants for dessert.

>Anthony Greer wrote May 21, re anaerobic substrates:]

>I know that this is moving away from the aquaria scale of things but if
>anyone is interested here it is...I work on freshwater swamp habitats in
>Southeast Asia and looking at soil cores from permanently flooded forest -
>it is possible to see a zone of oxidised Fe around the root hairs.  This
>sometimes amounts to large areas of aerobic substrate within a very
>unaerobic environment.  I have also  seen reference to some plants ie water
>hyacinth being able to transfer oxygen to their root zones and rhizomes and
>in this way create small pockets for aerobic degradation and nitrification.
>I know this relates to quite specific environments but if this is of
>interest to anyone in the group I can dig up the reference.

This has been talked about quite a bit on this list, and I think that most
long-time, regular readers of this list know that the roots of aquatic
plants have large air channels that allow oxygen to diffuse down these air
channels.  There has been quit a bit of research on this phenomenom, and
the literature has actual measurements of the oxygen concentrations in
various roots.  Tropica has an article on gas and water transport in
aquatic plants  (Its URL is http://www.tropica.dk/aqh1.htm).  This article
refers to a mechanism in amphibious plants and water lilies that circulates
air through the plants, allowing even faster transport than by diffusion.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174,
where summertime humidity and rains have finally arrived.