1800g of return flow is more than enough for a 200g. You will still need more flow in the display, so you WILL need extra flow in the display otherwise you will need to make a closed loop, but you have plenty of return flow. The amount of flow you have in your return would be fine for shrooms, zoas and softies, but you are way over on light for such critters.

What kind of corals do you gravitate to. Are you trying to create an sps tank, or do you like lps/shrooms/polyps. Given your lighting, which is huge, you are setup for sps, big time. Except you need more in-display flow.