Help Please: Leaf Issues

Hello... This is my first grow so I'm still trying to figure things out. I have 3 afgoo and 3 blue dream plants growing in soil under a 600 watt HPS. I have been growing for 3 weeks and I started flowering under 12/12 2 days ago. I water once every 2 or 3 days and I fertilize with fox farms grow big.

4 of the 6 plants are showing some signs of stress in their leaves. The afgoos (indica) are experiencing leaf rolling and the blue dreams (sativa) have rusty spots on their older growth. Also, the new growth on the blue dreams looks really bad.

I recently ordered a ph meter but it hasn't arrived in the mail yet so I have no idea what the soil ph is.

Thanks in advance for the help!

https://www.rollitup.org/general-marijuana-growing/24220-usefull-chart-problem-solving-anything.html

https://www.rollitup.org/general-marijuana-growing/1469-marijuana-plant-problems-cures.html

Im a newb on weed growing but your sides look burnt

and the pic number 8 looks like they need water all droopy.

i gave you some links to help with the problems

You have a nutrition problem. Most likely you will find that your ph is off.
When the ph is off various nutes get locked out. Check out a sick plant chart, I'll bet you'll identify more than one deficiency.