I run a 50 mg/hr on my 175 and it works fine to keep the ORP up around 350ish.
Your water will be noticeably clearer in one day, and much clearer in a week.
I did notice a difference when running ozone, and I don't think you're going to starve out your tank by running one. I pretty much have zero algae between that and my UV sterilizer. And UV works too, I've added to several tanks in the past after setting them up and you can noticeably see better health/skin/color/behavior on your fish within a couple weeks. I don't have time/space to do quarantine or hypo.
If you're going to do one or the other, get the UV. If you're going to do both, get the ozone too.
A good, high flow, high wattage UV will do about the same as ozone and a bit more to boot.