my small system used both gravel growbeds and rafts in the flood tanks.. the rafts did really well...

you could use "heavy duty" type rubbermaid tubs and to a gravel growbed, (add some worms to the gravel to help break down solids...) and do a timed pump to fill the gb a couple times an hour..or continous pump with a siphon

if you have a nice shelving unit, i'd have my ft in the middle, with a slo drain to a small sump (sized to flood your growbed) under the ft, with the plant tub on top..

you pump from the sump to the growbed, the growbed drains into the fishtank, and the fishtank drains into your sump