I thought I'd share with you my idea for feeding. Frozen food.
A stainless fishing cage.
Drop a frozen block in. Its tied to a fishing line and a sucker. Defrosts slowly in the tank. Fish know what's in it! Saves the frozen block getting sucked to the return grill!
Stainless steel will still corrode over time (how fast depends on exact composition of the steel). Good idea but I think the off the shelf plastic devices are better suited to our environment.