Looking to start growing autos in a 120 site system aeroponics using clay pebbles i will only be growing 60. I'll be Using flora series nutes. 4 1000 watt spyder farmer leds that cover a 5x5 section each light. Looking for a bases on ppm for feed. Where to start. I'll be monitoring the plants. But I want to start with a good number to build off of. Im making the switch from photos in Rockwool to this. So any advice helps. Thank you.