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Brown scum on pond surface
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Jnewbo
Jun 28, 1995, 3:00:00 AM6/28/95
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I have a tiny pond--just a plastic half-barrel sunk in the garden--and it
has done fine for several years, with lots of submerged oxygenating
plants, fish and frogs that actually overwinter, toads that use it for
spawning, etc. BUT this year I'm suddenly getting an ugly, thin brown
sheet or scum on the top, which I can "break up" easily but it returns the
next day. What is it? Any way to get rid of it? (I DONT intend to use a
filter or pump, I'm striving for a reasonably balanced ecosystem here!).
Thanks. Jud Newborn, LI
has done fine for several years, with lots of submerged oxygenating
plants, fish and frogs that actually overwinter, toads that use it for
spawning, etc. BUT this year I'm suddenly getting an ugly, thin brown
sheet or scum on the top, which I can "break up" easily but it returns the
next day. What is it? Any way to get rid of it? (I DONT intend to use a
filter or pump, I'm striving for a reasonably balanced ecosystem here!).
Thanks. Jud Newborn, LI
RGyure
Jun 29, 1995, 3:00:00 AM6/29/95
to
Sounds like an overgrowth of blue-green algae. Starts out innocent
enough-- looks like "healthy green stuff"-- but when nutrients rise,
growth speeds up, and the plants literally choke themselves -- as they
decay, oxygen is used up rapidly, producing anaerobic conditions which
kill the remaining algae-- results-- a dead brownish green scum. If
conditions of warmth and hi nutrient levels persist-- a second bloom and
die-off can occur in same season. My thoughts-- your pond is now more
mature and nutrien load has increased quite a bit since you first started
it. Natural treatment-- lots of aeration, removing a lot of the water
volume and replacing with fresh, for maintenance try to keep out any kind
of fertilizer runoff and any leaves, plant material that may be falling
in.
Of course, hand removal of algae helps a little-- but it grows right back.
Of course, some would advocate an herbicide application, and in dire
circumstances can be rationalized, but I like you would avoid that if I
could. Shading the pond also keeps it cooler and allows less sun for algal
growth-- sometimes a sunny corner allows for some nice plants-- but
keeping rest shade keeps down excess growth.
enough-- looks like "healthy green stuff"-- but when nutrients rise,
growth speeds up, and the plants literally choke themselves -- as they
decay, oxygen is used up rapidly, producing anaerobic conditions which
kill the remaining algae-- results-- a dead brownish green scum. If
conditions of warmth and hi nutrient levels persist-- a second bloom and
die-off can occur in same season. My thoughts-- your pond is now more
mature and nutrien load has increased quite a bit since you first started
it. Natural treatment-- lots of aeration, removing a lot of the water
volume and replacing with fresh, for maintenance try to keep out any kind
of fertilizer runoff and any leaves, plant material that may be falling
in.
Of course, hand removal of algae helps a little-- but it grows right back.
Of course, some would advocate an herbicide application, and in dire
circumstances can be rationalized, but I like you would avoid that if I
could. Shading the pond also keeps it cooler and allows less sun for algal
growth-- sometimes a sunny corner allows for some nice plants-- but
keeping rest shade keeps down excess growth.
RGyure
Jnewbo
Jul 1, 1995, 3:00:00 AM7/1/95
to
Many thanks for your fine comments on my "brown scum" (its more like a
thin glaze, actually). I think the immediate cause, as you hinted, may be
the following: I heavily fertilized my garden this year, and then there
were some heavy rains during which the pond surface rose above the ground
level--presumably the fertilizer then leached out of the soil and into the
pond, which retained it in high quantities when the waters receded.
thin glaze, actually). I think the immediate cause, as you hinted, may be
the following: I heavily fertilized my garden this year, and then there
were some heavy rains during which the pond surface rose above the ground
level--presumably the fertilizer then leached out of the soil and into the
pond, which retained it in high quantities when the waters receded.
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