DR2244

I have a Sovereign II (around 1999 or 2000) that has a leak I can't track down. It doesn't drain the tub lower than these two jets (photo 1) and the water leaks out down by the large black hose. It only leaks at the bottom of that hose and I can't find water anywhere else - I've ripped out behind all those jets and others and I don't see water coming anywhere in that area so I assume it's traveling somewhere along that big black hose but I can't figure out where that might be. What is that hose? It looks like it just houses a smaller hose/drain (??) I can't find any sort of plumbing diagram that will show me. Any direction/info much appreciated!