To our knowledge Copper Sulfate was the first chemical to be used for algae control. Although Copper Sulfate will kill algae, it is a product that we do not normally recommend.
Copper Sulfate reacts to the hardness of the water that it is being applied to, forming an insoluble salt called copper carbonate. The harder the water being treated the less effective the product is, in very hard waters, Copper Sulfate can have less than a minute of active killing time on the algae.
Even though there are more effective and safer products on the market, the use of Copper Sulfate for algae control is still very common, for two reasons, cost and ease of application.
In looking at a per treatment cost on Copper Sulfate versus the cost of Cutrine-Plus or Captain Algaecide, the Copper Sulfate is less expensive. Looking at it on a per treatment basis is misleading, many times the Copper Sulfate user will spend as much or more in a years time, since the Copper Sulfate will not give the length of control that the chelated copper compounds will.
One of the most common methods for applying Copper Sulfate is to put it in a burlap bag and drag it around the pond or lake in back of a boat, or simply to broadcast it by hand, there is no doubt that Copper Sulfate is easier to apply than a liquid compound that must be diluted and sprayed over the surface of the water.
Copper Sulfate is normally used at a rate of 10 lbs. per surface acre, Copper Sulfate unlike the chelated copper compounds, is very toxic to fish food organisms, and unless you are very careful can even kill fish. Toxicity increases as water hardness decreases.
Long term use of Copper Sulfate can actually lead to severe algae problems, although this must sound strange what happens is that over a period of years the copper carbonate buildup on the bottom of the pond actually will inhibit the growth of rooted bottom vegetation. Once rooted bottom vegetation cannot grow due to the buildup of copper carbonate on the bottom, the nutrients that this vegetation would have tied up is now available to excess algae growth.
We highly recommend that you consider using one of the chelated copper compounds, to avoid any loss of fish or damage to the natural balance of your body of water.
..
..
