Newbie need help - Flow Question.

[Aquattro]

Brandy, it's a tough question to answer, mostly dependant on your tank. If it's a softie or LPS tank, and the flow moves all the polyps around (for feeding/cleaning) AND the flow keeps the detritus suspended long enough for the filtration to remove it, you're probably OK. But, on average, for a 170g system, I'd say it may not be enough flow. IMO, a koralia 3 is good for a 20g reef, not something your size.
If it were me, I would have minimum 600gph per return line and at least 1600gph from each power head.
Well, for me as an SPS keeper, I'd have way more than that (last tank was 75g, about 8000gph total flow)
But, as I said, evaluate the behaviours above and see if the flow is currently doing what it should.