SE3000 ok for a 2'x4' grow tent?

For the shape of the tent, it would be a better fit. If it comes at great cost, could buy a 3x3 tent, if that is cheaper. They have very similar umol/s PAR outputs, so the primary difference is the shape. SE4500 12-hour operation - 90% is probably a good starting point 18h - 60% If the specs are accurate, this might be a better starting point than 67% / 100%. It's slightly overpowered for 8sq ft.