Most people with red sea 170's (reefer or e) seem to use Bubble Magus Curve 5 with success. There's a DC pump version of it, though people say it's not as good and creates far too many bubbles.
I am using a Simplicity 120 DC. It's quiet, looks nice, but my tank is still only a week into the cycle so it's not doing much (dead/dry rock and sand). I've seen others with good success. it's fairly cheap and has a DC pump so you can adjust the flow, bypass, and air all at the same time. A few other people I know have it on their Reefer 170 systems as well.