The Benefits And Costs Of Using Algaecides To Control Pond Algae

Ask just about any old time pond owner what he or she uses to control pond algae and the answer will likely be "some copper stuff". It's not uncommon to find that algaecides of all types have been used for many years to treat ponds that have turned green and slimey.

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.

To avoid this, it's best to treat smaller sections or segments of the pond algae bloom, rather that treat the entire pond at once. In this way, you can control the amount of oxygen depletion and algae die-off associated with the treatment. Do a bit at a time and you shouldn't have a problem with fish kills.

Unfortunately harm to fish isn't the only problem with algaecides. A much more insidious and problematic issue can arise with their repeated use.

Think of it this way. Anyone who know's anything about pond algae is aware that algae prospers in ponds where organic sedimentation is heavy. This organic "debris" is made up of decomposing vegetation like leaves, grass clippings, tree branches, or whatever else may fall in the pond at any given time.

Now picture this. When algae is killed by an algaecide and it dies quickly, in most cases it is not removed from the pond. It simply sinks to the bottom and begins to rot. As it does, just like the leaves and grass clippings, it will begin to raise the nutrient load in the water, just like compost might do in a backyard garden. This situation in a pond leads to more or increased algae growth.

So, with this in mind, the short term benefit of using an algaecide for a quick clean up of the pond is just that, a short-lived solution that will ultimately create the situation where more algae will be promoted, and since this algae will need to be treated, an endless cycle ensues that requires regular treatments.

This application and cycle also leads to an accelerated filling in of the pond due to sedimentation, which down the road, might require dredging or a full cleaning if the pond is a small backyard water garden.

In the end, many believe that although algaecides have some benefit, they should not be the first method of treatment on pond algae problems. Ideally it's best to look at other solutions that are less toxic, dangerous, and effective at cleaning the pond up of not only algae issues but of the organic build up as well.