No, each tuffbox is one grow site, and I run as many as a dozen in a given system. The tubs are never totally full, maybe up to 20 gallons each. Because I run waterfalls I can let the sites run almost empty with no ill effects. Add up all that capacity and you can see why I don't need a separate reservoir.
I get 27-32oz per plant.
Yes, waterfalls alone provide all the oxygenation and mixing I need. I don't even need to run a water chiller, anything from mid 60s to mid 70s is fine.
I grow each plant up a vertical trellis, 6' tall x 4' wide and SCRoG. I run 900W of COB LED using water cooled fixtures of my own design per trellis.
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She's two steps up a stepladder in this pic.