subject: The Benefits And Costs Of Using Algaecides [print this page] The most common kinds will most likely have some form of copper sulphate on the label and they often are in liquid or powder form. They have the advantage of working quickly to kill the algae and can work on surface and submerged algae types.
For the most part these products are relatively safe for desired plants and they are touted as being safe for fish as well. Due to this safety level and the speed at which they can work, they have been a favored approach to pond algae control.
But the question remains, "are they really the best option when it comes to pond algae control?"
While the manufacturers of such products will say yes, and reaffirm that they are safe when applied per directions, others have not found this to be the case.
As a pond care advisor I've had many pond owners contact me with the dilemma of dead or dying fish after applying an algaecide product. In effect it doesn't really matter what brand or what type. The reality is that if the product is designed to kill algae quickly, and it is applied in a certain situation, it will likely result in a fish kill.
The problem is not so much in the product itself but in the fact that if a pond is heavily infested with algae and much of it is killed off quickly, there is a high probability that the die-off will pull a great deal of the oxygen out of the pond very quickly. When this happens, unless the pond owner has taken steps to increase aeration, then the fish will likely suffer and some will die.
