carlrs wrote:

On Jul 4, 4:44 am, (Peter Ashby) wrote:
Our 10gallon community tank has been going on perfectly happily for
several years. Then in the last year we have been battling blue/green
algae. Now my best understanding is that this is usually a symptom of
too much phosphate. So where has this phosphate suddenly come from? I
have begun to ask myself. It must be something I am adding to the tank.
About 18months ago I switched from flake food to Tetra Prima, the orange
granular stuff. Largely because we have no surface feeders anymore, just
scissortails and tetras in the midwater.

Now a perusal of the ingredients reveals L-ascorbyl-2-polyphosphate,
obviously a VitC derivative which is almost certainly in there as a
preservative. Both the Tetra algae wafers and tabimin food for the
bottom feeders have it too. IIRC we swapped from a Japanese algae wafer
to the Tetra stuff too. So there I seem to have a cause.

We have an air driven ugf (works just fine for us) so removal with ion
exchange resin is not practicable. So I am trying to dilute it out,
which will not work unless I change the food I have now realised (they
have been eating frozen the last 2 days).

Any comments, suggestions?


There are several parameters that can contribute to Blue-Green Algae
(Cyanobacteria), and so far as to my research no one parameter has
had a smoking gun as to being proven to be the main contributor (and
none may either). I personally have been focusing on the Redox
Potential in my research (a Redox potential of -300mV seems to be best
here). A GH over 100 + will contribute necessary electrolytes to this.

This said nutrients in the water column are certainly an issue as
well, phosphates being one of them. Many manufactured foods are high
in ash (which often includes phosphates) and Tetra is one of the worst
offenders. I recommend more basic simpler fish foods such as Spirulina
20.

I have usually been able to control/prevent BG algae in my client's
aquariums with a shot gun approach of addressing all the contributing
factors and applying as many treatments/remedies as possible.

This articles deals with a few suggestions as to BG Algae:

http://aquarium-answers.blogspot.com...gae-in-aquariu
ms.html

Thanks for that, the tank has always been acid and soft. It was like
that for several years before the b/g came around. I'll try changing the
food with lots of water changes and keeping it very clean and see how
that goes.

Peter

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