Your own mix does sound the best way to do it I'm sure - I have heard that they shouldn't gulp air at the surface - when I feed them about half of the food sinks straight away which they do eat first and then the rest is pushed down into the water by the filter outflow, but my big male always likes to be greedy and eat some at the surface too... Do you think I should stop him?! He's been doing it all his life and it CERTAINLY hasn't stunted his growth!