Automatic feeders are extremely dangerous for aquariums. In case of a possible overdose feeding, you may loose your animals due to phospate, revealed by uneaten food. So it is better not to use automatic feeder. First of all fish are very resistant to starvation. They can easily live more than two weeks without eating anything. On the other hand, if there is enough lightening, plants, other animals like shimp etc, decorations like mangrow, fish will fing something to eat. So it is better not to use automatic feeding machines at all.