(~Roy~) wrote:

Runoff from the land into any body of water brings extra nutrients,
which all lead to feeding algae. I don;t know if I would go the coper
based route, but they use it around here with good results. heard both
ways it hurts or kills fish and invertabraes and also heard if done
properly it causes them no harm. I use aluminum sulphate (?) common
alum which is marketed as Baraclear-80 which locks up the phosphates,
and it has made a remarkable improvement in my waters looks and
virtually reduced my algae to nothing. A super feat for the zone I
live in.

Actually alum is an ambiguous term. Alum can be any one of a series of
isomorphous double salts that are hydrated sulfates of a univalent
cation (e.g., potassium, sodium, ammonium, cesium, or thallium) and a
trivalent cation (e.g., aluminum, chromium, iron, manganese, cobalt, or
titanium). The name alum commonly refers to potassium aluminum sulfate
dodecahydrate, or potash alum, KAl(SO4)2?12H2O, a colorless-to-white,
crystalline compound. Straight aluminum sulfate would work best in a
pond because it will tie up the potassium and form potash alum.

I am not sure of the dynamics of aluminum sulfate in a pond, but on
land, the aluminum sulfate will eventually poison the soil. The
aluminum builds up to such a high level that it destroys microorganisms
in the soil. This was learned with blueberries. Farmers applied alum
to the soil to increase the acidity. This worked wonders, but
eventually the blueberry plants started looking bad and stopped
producing. The aluminum in the soil was the culprit. In acidic soils,
aluminum ions are toxic to nearly everything that lives in the soil that
is beneficial to berry plants and builds up over time.

Most extension services state:
"Aluminum sulfate will also lower pH, but it is not recommended as a
soil acidifying amendment because of the potential for aluminum toxicity
to plant roots."

for examples see:
http://www.ext.colostate.edu/pubs/garden/07727.html
http://www.extension.umn.edu/info-u/plants/BG497.html
http://web.extension.uiuc.edu/champa...rs/020622.html
http://www.hgic.umd.edu/pubs/online/hg11.pdf
http://www.ahs.org/040329_TAG/M_J25-29.pdf
http://www.justfruitsandexotics.com/JF%20Blueberry.pdf
http://www.rce.rutgers.edu/pubs/blue.../bb-v20n18.pdf
http://www.sln.potsdam.ny.us/how-to-plant.html

Unfortunately people that sell alum/aluminum sulfate still recommend it
to acidify soils. They also sell you more plants when your old one dye.

By the way, Tom's of Maine sells buffered aluminum sulfate and calls it
tooth paste. Deodorant companies call it an antiperspirant.
--
Pardon my spam deterrent; send email to
18,000 gallon (17'x 47'x 2-4') lily pond garden in Zone 6
Cheers, Steve Henning in Reading, PA USA