I saw a tip in Birds and Blooms magazine that suggested putting some copper pennies into a birdbath to keep algae growth down. I wouldn't do that with ducks b/c the goobers would probably eat the pennies and the acid would eat off the copper allowing the zinc to leach out & poison them, so I know that's out. However, would a length of copper pipe (too big to "bill" or lift) in the bottom of the pool have the same algae-inhibiting effect? ?? anyone know for sure? or alternatively, how do you keep the algae out of your duckie pool? (it's as much in the shade as I can get it). TIA!