seems like a good idea make your to read up on hydrophonics and keep us updated , only problem i see is with the can pumping the water the turn over rate might be to high as plants require a pretty long dwell time to soak up the waist in the system .
Then I could maybe use a powerhead to feed the sump... this should decrease the flow rate (which the plants would benefit from) and use "untreated water"... and I'd stick to the original design and not use the filter sock...