Correct. For my "Closed Loop" water is pulled into my dart from the overflow on the end of my tank. It is pushed out from the lock line in the bottom of my tank. My center overflow drops water into the far end of my sump. On the opposite end, water is pulled into another dart and pushed out of the lock line on top.
Hope that helps!
Perfect understanding now. I am going to incorporate this in my next build, any feed back on using an ocean motion? Doesn't look like you're usin anything like that, any reason? Thanks for taking the time to respond. Hoping to take my 125 reef to a 1000gal reef within the next year