White Widow ( First Grow )

Greetings from Canada! Welcome to my first grow. I thought i ordered autos but received feminized photos lol (100% germination paper towel method! ), must've been stoned when i ordered 😂😂. Oh well, here we go. Lights are 2x 1500w hollandstar COBs off amazon, true draw around 220w a piece. Feeding straight RO water as it comes out of the filters at around PH 6.5 ( tested with PH drops/meter ). 5 Gallon fabric pots mixed 50-50 FFOF/ProMix HP. Only Watering them around the seedlings and taking precaution to let the medium dry out a fair bit in-between waterings. Will be switching lights to 20/4 at the end of day 7. I suspect the tent will drop to about 19 Celsius during those 4 hours of darkness as my basement stays at around 20 Celsius. Will attempt LBHs' tutorial on scrogging after the first set of 5 finger leaves develop.