Thats awsome man! They are so much fun to watch and they always seem to chase each other and make each other jump around when they come face to face with each other lol
I feed my tank once a week and feed them like 3 - 4 fish flakes, i would probably take 1 to 2 large flakes (broken up but not powdered) and drop that in the tank and make sure it sinks to the bottom. I have seen mine eating at the algae thats grown on the waters surface but its very rare, probably because they have fish food flakes to eat. I'm not sure how well they will pick up algae powder with their large claws to be honest.