You need to add Hysteresis on your tanks and storage units.

There needs to have the ability to only fill a tank when it reaches (for example) 25%, but FILL it to 100% then stop until it reaches 25% again. Otherwise you are just reducing the overall capacity of a storage unit/tank or constantly trickling in parts as they are consumed. This is terribly inefficient.

I was just about to add this only to see it already here. Hard to believe this hasn't been done yet - the current state of storages is almost as useless as possible. The keep full and empty sliders just need to be trigger points for filling or emptying the whole thing.