Get a better overflow, haha, lol. j/k
I've heard many people say that you need to hook up a bleeder tube to the ventury intake of a powerhead to keep those things primed, I'd look into that, also make sure you have enough flow, I don't know the flow on either the pump of the overflow you listed.
But seriously, from what I've read you might look into a u-tube overflow, I'm ordering one myself in the next fews days
But don't take this as gospel, I've not used either "yet"... GL