Flow for 36 gallon bowfront.

I have a 36 gallon bow front tank that's been set up for almost 8 months now. It has 40 lbs live rock and 30 lbs live sand. currently I only have 2 maroon clowns, a brittle star, a tan emerald crab, an arrow crab, and a bunch of snails and hermits for cuc. I recently got a reef octo protein skimmer 90 and took off my aquaclear 50 filter as I read they where nitrate factories and my nitrates had started to go up. I had two koralia 450's but just upgraded to what I thought where 750/850 as sold on amazon but looks like they are just 2 850's. is this to much flow for this tank? My plan is to add a bta along with some lps. prolly no sps. with both going it moves the sand a little but doesn't create bare spots or anything. It does make pretty good surface agitation. I could use one 850 and one or two 450's. just want to get some opinions if anyone else is running this tank and what they use for flow and how to best position power heads.