Manifold and Pump Size?

Hello again, <<Hello Randy>> Thanks for the advice given below. <<Hope it was useful>> I went ahead and got myself a slightly used Iwaki MD 100RLT from a fellow reefer to power the closed-loop (way too expensive to buy a new one). <<A good choice and surprisingly quiet for their size/flow-rate... in my experience>> I am about to upgrade to an Oceanic 72 RR bow front that has the mega-flow overflow and now some new dilemmas have arisen. <<Oh?>> Underneath I am going to be setting up a 10 gallon refugium that will be fed by a T coming from the tank drain w/ a valve to slow down the rate and then gravity flowing at a slower rate into a 10 gallon sump w/protein skimmer, etc. <<Ok...but rather see use of larger vessels if possible>> So now that you have an idea of the setup here are some questions that I hope you can help me with.  more