Have an asm G3 on my 150, at first i hated it, set it up appropriately in a seperate compartment that is stable and is first section in the sump, barely able to squeeze it in.. put the pump with the output directly into the skimmer, not using the ell, put a 3.5 inch couple with a 3.5" septic tee from home depot. Low and behold with 3 small fish, it will give plenty of crud. Sand is starting to look cleaner. also in that improved circulation in the tank so that you can see food just swirls around, it never has a chance to settle down to the sand. Fish have to catch it in the water column.
Went from most i could get was about 1/8" of skimmate day and foam only getting over the riser not turning pass the lid back into cup, put in like the above now, it fills the cup half full of foam.
G3 can work, but I almost ran out of patience with mine. I thought it was setup stable with being in a seperate been in the sump, but never did get it going like that.