I have 2lb per gallon of lr, a 4in dsb, bio-balls, a 12 gallon refugium built in my sump(all acrylic) and a monnster of a skimmer.
My refugium is on one end of my sump right next to my chamber with the return pump. I have a 201 ph in the main chamber that has airline tubbing pumping water into the refugium. And the water overflows back into the camber with the main pump. This elimanated having to get the water compatiable with the tank water. I put a dsb in with 10lb of lr and let it sit about a week before addind any kind of culerpa or macro algea. Now I have more of either than I need. I have a 13 cf over the refugium and all is well!!