There is a theory that mankind discovered the biocidal properties of copper by accident when throwing metal coins into a wishing well. They found that the water was not only safer to drink, but also tended to render people less prone to common bacterial infections. 

Fast-forward a few hundred years, and pool supply stores today sell copper sulphate as an algaecide for swimming pools. 

What is the basis for this? How safe is copper sulphate? What is it anyway?

What is Copper Sulphate?

Copper sulphate is a blue crystalline chemical compound, also known as bluestone. It is the result of the reaction of copper oxide to sulphuric acid and enjoys many uses such as a fungicide, herbicide, and algaecide as well as creating that gorgeous blue colour in fireworks. 

The fact that this compound is so effective as an algaecide, plus the fact that it’s highly soluble in water, makes it an excellent option for swimming pools.

However, care must be taken when handling copper sulphate as it can be corrosive to the skin and eyes. It is safe to use in your swimming pool, yes, but under the right conditions and in the right way.

When using copper sulphate as an algaecide, you will need to first check the Total Alkalinity of your pool water. If it falls below 50 ppm or above 200 ppm then this will need to be corrected first – you should have a reading of between 80 – 120 ppm.  

Carefully read the label on your copper sulphate product before use. This will help to determine how much you need based on your TA reading and your pool size. 

If incorrectly applied, bluestone can stain the walls or floor of the swimming pool. Ideally then, once you have the correct mix for your unique needs, its best to use a spray and pump bottle and methodically cover the entire surface of your pool. This allows for an even distribution of the product. 

Be sure to wear a face mask if you are using this spray method of application, as breathing in copper sulphate aerosol fumes can damage your lungs and airways.

How soon can you swim after dosing your pool?

That depends very much on the product specifications (always read the label) but if done correctly, you should be fine to swim within an hour. 

For more detailed information please feel free to contact the Pool Spa professionals.