I am new to hydroponics and aquaponics. I've supervised drilling of six water wells and designed/ built various water storage and delivery systems in the 60psi/ 60gpm range. I have also built fountains of many kinds. The koi ponds I have built used about 2 yards of 3/4" crushed gravel as a biofilter, as well as a sand filter. The gravel is removed, washed, and replaced annually at considerable effort.(which I am no longer involved with!) I am very interested in the incorporation of vermiponics as a media penetrant and source of beneficial plant nutrients. (to minimize/eliminate above mentioned gravel manipulations)
I further imagine an ebb and flow vermicomposter, where the compost material would sit atop gravel and "high tide" would be about 3" below the flats of compost material. With a 2" dia. fast flush syphon (to carry solids) the resulting compost tea could go into upstream hydroponic beds. Hopefully these beds would also be infested with worms. (only 2 high tides/day in vermicomposter)
I have built nothing and have a negative project budget, but there is little option. Fukushima is quickly eliminating the Pacific as a healthy food source. It is not in the news. (see: http://fairewinds.com/ for expert radiation perspectives) Environmental and economic forces are conspiring to force the prudent down this path of semi self sustainable aquaculture. I am glad to find that not only am I not alone, we are almost legion.