I'll be setting up my 125 this weekend and my sump is a 40 gal that is 17 inches high. After setting the ASM-3 in the sump, the riser tube is just as high as the top of the 40 gal. sump!!!
One thing to watch out for with the ASM skimmers is the intake hole for the air tube gets clogged with calcium build up over time.. If you see more pressure coming out of the riser tube you know that it's time to clean it out. Otherwise I have been very happy with my ASM.
