Your probably right Ken ... I've never really gone back to one years later to see if it is still working. It's a cheap Fix sometimes. Whenever I have done one I also incorporate a large rock filled pit.
Chuck ...I 've done it both ways, but like I said i've never really followed up years later so I can't say for sure. I do agree that filter cloth will clog over time. i would use 3/4 clear instead of crush.