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Re: red algae & CO2

Neil Frank wrote....
>These
>observations seem to contradict the advice of the Germans. They recommend
>introduction of CO2 to suppress the growth of red algae

And they've done so much research.

>[As I indicated elsewhere, I never saw mature red algae in my tanganyikan
>tanks where I suspect free CO2 shifted to bicarbonates]
>
>The FAMA article also says.......
>"It has been shown that the addition of gaseous CO2 or lowering of PH
>stimulated the shift from blue-greens to green algae. This shift can occur
>when stratified water conditions are artificailally circulated or
>aerated.... causing CO2 to enter from the atmosphere."

When one aerates and increases surface circulation CO2 exits the tank
and oxygen levels rise. That's how I rid my 180 of BG algae a couple
of times. Rataj mentions this. It has, however, been my experience
that lowering the pH sometimes triggers BG disintegration.

Glen Osterhout wrote....

>> From: ac554 at freenet_carleton.ca (David Whittaker)
>> Subject: PMDD Paper
>>
>> "Because others have observed that tanks with CO2 fertilization have
>> relatively little red algae [5], it tempting to speculate that at
>> least some red algaes are able to utilize bicarbonate, giving them an
>> advantage in aquaria where most of the available carbon is in this
>> form (typically those with high carbonate hardness and high pH)."
>>
>> "Red algae is favored over green algae if most of the available
>> carbon is in the form of bicarbonates."
>
>I'm sorry to have to rain on the parade here,  but my experience
>doesn't support the theory that co2 stops red algae. 

Neither does mine. It's not my parade and it wasn't my float.

>About 3 or
>4 weeks after I set up my plant tank,  before the plants were 
>fully established, I tried turning on the co2 to speed up the
>process.  The result was a sudden and impressive plague of red
>algae that threatened to smother everything.  This was only
>countered by the introduction of a dozen Siamese algae eaters.
>The variety of red algae was not the usual dark green brush,
>but a variety with reddish, long, fine strands which looked a
>lot like masses of hair (ychh). There may be conditions where
>co2 favors other algae and plants more than red algae,  but
>this is not guaranteed to always be true. 

My experience was identical to yours except that I got both
types of red algae and I don't have 12 SAEs on hand. My water
is very soft and CO2 acidified. The PMDD killed the black
brush algae replacing it with a green coloured form yet to be
identified.

--
Dave Whittaker                       ac554 at FreeNet_Carleton.CA
Gloucester, Ontario                  dwhitt at magmacom_com
Canada