How do copper stains occur? Copper stains in your swimming pool can occur due to copper based algaecides, poor quality pool salt, copper pool heating pipes, bore water, or a chlorine free pool system. These products add invisible copper ions to your pool water. If the copper ions are not properly removed, that’s when the staining can occur (especially if your water pH exceeds 8.3). The high pH levels will cause the copper ions to suspend in the pool water or stick to the pool surface- this is where you get the discoloration.
Signs you have copper staining in your pool: color stains that do not brush away, the stains get worse over time, the stains slowly change color, and chlorine treatment makes the stains darker.
Due to coppers similar appearance to algae stains, people sometimes shock their pool with chlorine which actually oxidizes the copper staining. The chlorine shock will make the copper stains much worse! Not all copper stains are created equally so before treatment, you might want to consider a professional opinion.
It’s wise to remove copper staining from your pool as soon as possible. It’s also wise to identify the source of the copper to prevent further staining.