alfdaddy,
wafflehouselover has a nice breakdown on his DWC experience here:
https://www.rollitup.org/hydroponics-aeroponics/23939-my-first-time-dwc-journey.html
I'm gettin ready for my first hydro grow and have been doing a bunch of research on it...especially DWC cause it seems like you can get good yields for not much initial outlay. Looks like wafflehouselover is on the right track, plenty of space in your reservoir (probably 30gal rubbermaid for 6 plants is good, 18gal for 3, etc), I'd maybe use more airstones than just 2 x 6-inchers, I think probably 4 X 12" stones with a good air pump behind them. I think the algae problem you had could have been a factor in your first dwc meltdown- from what I've read DWC growers have to be very diligent in making sure that no light gets into the reservoir, otherwise algae starts growing in there and messes things up... unless you covered the sides of that fishtank I bet tons of light was getting in through the sides. You need an opaque container like a black rubbermaid, and make sure no light gets through the top where the nets sit in the holes you make in the lid.
Seems like with that much space you could get a pretty good grow on- even though you wouldn't be getting a constant harvest, you could veg under your MH then switch to the HPS for flower, with 6 plants in one 30gal dwc setup you could probably pull a nice amount of buds off it, letting it bush out into your space with some kind of netting or screen to maximize your 4x2.5 area. I don't think the approach of having all plants in one container would be good for seedlings though, since if you discovered you had males you'd have to mess up root systems getting them out once they showed in flower, so maybe you could grow in individual 5gal buckets, or do soil until you have some mothers you can make clones from.
I dunno, I'm still reading up on this stuff at this point...