Hi cport15!
Your problem is actually familiar to me as my first pool was a 15' Intex Donut with the same problem. I solved it by using a 3/4" PVC connector (called a "Double Female"--sorry, that's what it's called) that stuffed into the vacuum hose and into the side-wall drain. It was a perfect fit and would get the finer stuff that they Black Magic garden-hose jet system couldn't catch--the bag isn't fine enough.