I'm just putting my thoughts out there,you make the final decision...okay,I use two 600 watt lamps and an open grow( no tents) this allows me to adjust the "footprint" of the area,I tried to do 50sf in the past( 2 areas at 5x5) with the open grow and no training 6 plants under each light ended up needing more space than the 50sf,this was with no training,my current grows have started out at 4x4 area and quickly outgrow that,I can adjust since it's open but HID lighting loses efficiency pretty quickly trying to light a 5x5 or 6x6 area unless a flat even canopy is created,I can honestly say that the 2 auto ultimates with a proper scrog would fill that same 4x4 or even a 5x5 area,,my advice would be to start with four plants per light in a 16sf area to utilize the scrog to its full potential ,you can always do more plants later but don't make it frustrating to the point that it causes problems,don't forget about watering, maintenance and airflow.sometimes less is better!!..lastly AU is considered a "medium" sized plant but mine are 43 inches tall,try some x-small/small framed strains if you want/need more plant count,this might be what ur looking for...peace
