ok first of all i am kinda confuzed on what it is your are discribning but ill try and help! no pump to get water from your tank to your sump, have it done by gravity. to do that you will meed to take all the air out of the high part of you pvc pipe by sticking iar line up it and sucking the air out with your mouth (yeah i know kinda gross buy you have eto do it) i like the idea of pvc to get water from the tank to your sump, its cheap/easy and it sounds like it will work. on now it sounded like you wanted to use 2 10gallon tanks? sounds like more of a hassle than what it is worth, go buy a 20gallon long. the buble baffles are not really to stop bubles from getting in the water like you are thinking, what they do is make the water calm. if the water was turbulent air will get sucked into your pump and blow air bubbles all over your tank. for what i understand with having a refugium is you will only need like 1/5 of the filterd water to run into it do you can eather plit your water tube going into your tank and have a valve on it or use a really small pump/power head and some tubing to get water into it. as for stuff to have in your refugium i have herd of people using brittle stars, lr, ls, different filter feeders, alot of plant life, cleaner clams, bristle worms, shrimp, snails, crabs, and other stuff. just remember about lighting your refugium. one of the main reasons for having a sump is to increase your water volume and to hide your heater and protine skimmer, and the refugium is for aditional bio filtration. i gope i was able to help you with what you are planning to do. if you plan to make your ouwn sump/refugium go out and buy some plexi glass for your bubble baffles.