http://edis.ifas.ufl.edu/FA008



If the total alkalinity is less than 50 ppm, copper treatments are not recommended because of the high risk of killing fish. If the total alkalinity is over 250 ppm, do not use more than 2.5 ppm of copper sulfate. Florida's waters are extremely variable in alkalinity, so if you don't know the alkalinity of your water, find out before you treat with copper. In the literature you will see many different values for copper dosages, but experience has shown that the above formula is best for determining the dosage rate.



Chemical Upper Limits for Continuous Exposure and/or Tolerance Ranges
Ammonia (NH3) 0.0125 ppm (un-ionized form)
Cadmiuma 0.004 ppm (soft water < 100 ppm alkalinity)
Cadmiumb 0.003 ppm (hard water > 100 ppm alkalinity)
Calcium 4.0 to 160 ppm (10.0-160.00 ppm d )
Carbon dioxide 0.0 to 10 ppm (0.0-15.0 ppm d)
Cholorine 0.03 ppm
Copperc 0.006 in soft water
Hydrogen sulfide 0.002 ppm (Larsen - 0.0 ppm)
Iron (total) 0.0 to 0.15 ppm (0.0-0.5 ppm d)
Ferrous ion 0.00 ppm
Ferric ion 0.5 ppm (0.0-0.5 ppm d)
Lead 0.03 ppm
Magnesium (Needed for buffer system)
Manganese 0.0 to 0.01 ppm
Mercury (organic of inorganic) 0.002 ppm maximum, 0.00005 ppm average
Nitrate (NO-3) 0.0 to 3.0 ppm
Nitrite (NO-2) 0.1 ppm in soft water, 0.2 ppm in hard water
Nitrite-nitrogen 0.03 and 0.06 ppm nitrite-nitrogen
Nitrogen Maximum total gas pressure 110% of saturation
Oxygen 5.0 ppm to saturation; 7.0 to saturation for eggs or broodstock
Ozone 0.005 ppm
pH 6.5 to 8.0 (6.6-9.0d)
Phosphorus 0.01 to 3.0 ppm
Polychlorinated biphenyls (PCBs) 0.002
Total suspended and settleable solids 80.0 ppm or less
Total Alkalinity (as CaCO3) 10.0 to 400 ppm (50.0-4.00.0 ppmd)
% as phenolphthalein 0.0 to 25 ppm (0.40 ppmd)
% as methyl orange 75 to 100 ppm (60.0-100.0 ppmd)
% as ppm hydroxide 0.0 ppm
% as ppm carbonate 0.0 to 25 ppm (0.0-40.0 ppmd)
% as ppm bicarbonate 75 to 100 ppm
Total Hardness (as CaCO3) 10 to 400 ppm (50.0-400.0 ppmd)
Zinc 0.03-0.05 ppm





Copper sulfate
(Various trade names)
Copper sulfate is a contact herbicide
primarily used to control
algae. However, it is not effective
for Pithophora control. Copper
can interfere with gill functions
and, if improperly used, can be
toxic to fish and zooplankton.
Fish species such as trout and
koi are particularly sensitive to
copper. However, most fish kills
that occur after copper sulfate
treatment are caused by a massive
algae kill and the subsequent
oxygen depletion.
Copper sulfate is also formulated
as a solution made by dissolving
the crystals in a sulfuric acid
solution. These acidified copper
solutions are registered for aquatic
use and sold under various
trade names (e.g., Copper Cat,
EarthTec, AgriTec, etc.).
The effectiveness and safety of
copper sulfate are determined by
alkalinity and water temperature.
In water with an alkalinity ≤ 50
ppm, the rate of copper sulfate
needed to control algae can be
toxic to fish. Copper treatment at
water alkalinities of ≤ 20 ppm is
extremely risky. In high alkalinity
(≤ 250 ppm) water, copper sulfate
quickly precipitates out and
is not effective for algae control.
The toxicity of copper sulfate to
fish increases as water temperature
increases. Avoid copper sulfate
applications during hot summer
months. (For additional
information on treating with copper
see SRAC Publication No.
410, Calculating Treatments for
Ponds and Tanks.)

Last edited by ewest; 03/13/08 01:12 PM.