They are eating hair algae, cladophora, and repashy shrimp souffle (in that order)
Mine eat algae, shrimp food, fish flakes, veggies, they're not picky. They love blood worms, but they should only have them once in a while as a treat.
I'd go easy on the shrimp pellets. The protein content is too high to be a staple in their diet. Also, some have trace metals that are ok for fish, but can build up and cause problems for shrimp.
I have never experience an issue from the small amounts of copper found in prepared foods. I fed them for years before there were other options and never had any issues wiht longevity or breeding. That being said, there are better diets now available. The reality is that amanos will eat just about anything, so don't need specialized foods.