I am growing under COB LEDs. Lights are about 18 inches from plants running them 24/7 for now. I just had to fire up another two rows so I will likely go to a 20on 4off schedule to keep Temps down. Temps vary from upper 60s to low 70s. I am in Happy Frog soil. I am using Aurora Roots Organic nutes. Water is ph 6.5. Runoff seems show ph of around 7 usually. I had some leaves start to show yellow spots with brown centers at week 2 of veg. New growth was fine for a couple weeks then more showed up last week. Plants just finished their first week of flower and are a total of 5 weeks old. I took a pic of the whole plant then a close up of the issue. 3 plants look like they all have either a calcium or magnesium deficiency. The 4th onew just looks to have a few leaves turning a lighter green like theyou are going to yellow. That plant seems to have a different issue.