Heres 19 in my tray right now pushin 3.5 4 ft 17 glufies and 2 forum cookies.
From the day they leave the clone dome they get started on 50ml/40gallons and work their way up . Usually 1.0 1.2 ec in flower
Ya another scale of reading levels. 1.0 ec is 500 ppm on my meter.
How many cubic feet is the room? What are you running in/out fanwise? Have a carbon filter to match?? What size is that res? I run 40 gallons and sometimes by water change day, pumps close to suckin air.