You can really never have too much flow. The more the better. From what I have read, you want to try and aim at turning your tank water over at bare minimum 6-10 times per hour. Your Rio 800 powerhead is 211gph. You have a total of 772 gallons per hours. You tank water is being turned over 16.4 times per hour. Depending on what kind of tank you have (Fish-only, FOWLR, Reef), a lot of people go for 15-20 times per hour. In other words you should be just fine. Some people will say you can never have to much flow, some will say you can.