this is my eco-system. i could've saved some money building everything up from the ground. however i decided it was probably too much work for me since it was my first semi-diy project. even now i'd still opt for a pre-made thing than putting all pieces together from the ground up.
the water comes down from the overflow to one of the two holes on the left. this is the first area, you use a flexible tube to connect from the bottom of the overflow to the sump (which i will show later.) then you can either just let the tube drop in like that or you can wrap it around with some kind of clothes.
the water will go through the two 'eyes' and reach to the middle 'refugium' section. then the water will then over flow to the next chamber which is the sump for the pump. and the pump pumps the water back up to the main display.