I'm researching different grow media for my duck pond bio/ wetland filter. My thought was to include a long stream in my pond water system (before entering the barrel filters) that would help filter out the nitrites and nitrates. Basically aquaponics with reeds or other duck friendly plants. But as it is on ground level it will be accessible to ducks, so I'm concerned about them eating the grow media. Does anyone have experience or insight into their interaction with lightweight expanded clay aggregate or expanded shale? I'm afraid they will try to eat the clay balls and choke. I was considering lava rock but I understand that it is sharp and I didn't want them cutting their feet. Thank you for your help!
