We have had the black clump day algae for four years. It sinks at night.
No fish loss from it thus far...but then we have our circulation on 24/7.
Jim scoops it off with a net when it gets to be too ugly. That reduces it
but does not remove it. It seems to form on the bottom and then break free
to rise up...or maybe it it just falls to the bottom and then rises up.
Ugly, but apparently not harmful.

P

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"Lee Brouillet" wrote in message
...
ACK! Any chance it will go away by itself? Like some of the others, I
think
I had this last year (earlier than it showed this year), and it was
contributory to a fish kill due to lack of oxygen. It clumped into
malevolent black islands that rose to the surface during the day and sunk
at
night, where it promptly consumed all the O2. This year I have airstones
that I run 24/7/365. Where does it come from and how do I get rid of it???

Lee
"GD" wrote in message
...
It is a Cyanobacterium (bluegreen algae). Oscillatoria spp. I
cannot tell the species from your pictures, but that probably doesn't
really matter.


"Lee Brouillet" wrote:

OK, I have a problem. My otherwise pristine pond water had developed
suspended algae - large stuff. It *will* clump, but most of it's being
removed by my pre-filter. I just posted shots of it on my "website"
below.
There are microscopy shots of it at 40, 100 and 400X. If you have any
ideas,
please let me know!