Tizzo, the overflow in the upper right drains the DT down into the right chamber in the refugium where my protein skimmer is, it then flows under the bubble trap into the actual fuge area. Then it flows over and under another bubble trap into the left compartment which then goes through the pump back up to the DT on the left. The water level in my DT stays the same because of the overflow. The water in the fuge fluctuates because it it under the DT. All I did was take a 20g and buy 5 plexiglass baffles cut to size, then siliconed the bubble traps in. In the picture there are 2 on the right and 3 on the left. If your fuge is below your tank, have the baffles cut to 65%-75% the height of your fuge. You dont want to have full capacity in your fuge, because when the power goes out, the pump stops pumping water back up to the DT, but the overflow will drain to the top of itself, which in my 55g puts another 2-3g back into the fuge during power outages. This takes the water level in the fuge from about 15g to 18g, with 2g to spare. If there's anyelse you don't understand just ask.
