SUPER SIGH AGAIN

120v-> hydrofarm-> Ve200->rack

Flexwatt(rack) ->VE200->Hydrofarm->wall outlet. Therefore VE200 is main

You follow the path of power supply, not draw.

wall outlet->Hydrofarm->VE200->Flexwatt(rack)

Therefore your Hydrofarm is your main, just like in a circuit panel your MAIN breaker is the closest to the incoming power source.