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re: removing an algae bloom ?
9 jun 1998
dave h. wrote:
>...last weekend the water started turning green, and you could not
>see much below the surface. can this bloom be removed...
a tiny amount of copper ion kills algae,
eg 5 parts per billion from copper sulfate.
>...or let it take it's course, or what.
letting it take its course might work. the algae may indicate a "bod"
(biological oxygen demand) from some leftover decaying organic matter.
what's the bod output of a fish? is there a limnologist in the house?
oxygen naturally diffuses into a pond surface from air, and algae
supply oxygen too, a total of about 100 pounds of o2 per acre per day
from both sources in 20c sewage treatment ponds containing about
100 mg/l of algae, according to table 10-20 on page 645 of the 3rd
edition of metcalf and eddy's "wastewater engineering," although
those ponds have a low dissolved oxygen concentration (1 or 2 mg/l)
compared to minimum levels for fish (4-5), so the oxygen uptake rate
(which is proportional to the difference between the saturation
solubility (eg 9.17 mg/l at 20c) and the actual concentration)
is greater for those ponds.
perhaps algae can be our friends, quietly adding oxygen to water,
unlike more energy-intensive fountains or air bubblers. a fish pond
might have a nearby algae pond or algal section for oxygenating fish
poop, with water (but not fish) slowly circulating between the two
during the day (with a solar powered pump?), but not at night, when
the oxygen level in the algae pond can drop low enough to kill fish.
nick
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