If you're interested in looking at iAVs, start here ....http://iavs.info/ Plenty of information once you figure out how to poke around in the site. I've been running an iAVS system for a couple months. Got rid of my original gravel based F/D system. Gotta say, iAVs is "as advertised". The hard part is sourcing the proper sand, but once that is done everything else is quite simple and easy.