Will Pennies Kill Algae?

No, it will not but you need to make sure they are pre 1982 pennies. There is a lot of zinc in pennies minted later than that & that could possibly harm the birds. Copper kills fish. There is no doubt about this.

Will copper pennies kill algae?

Copper's Effect

It kills algae by binding to it, which damages the algae cells, causing them to leak and die. ... Too much copper is toxic to plants because it prevents photosynthesis.

Can I put pennies in my pool?

Since Roman times, the soldiers added a silver penny into their water canteens to keep their water free from bacteria. So adding silver to a pool in conjunction with copper makes an awesome powerful chemical free swimming pool water sanitizer. This is great for the environment as you are not using chemicals.