Need help identify leaf issue.

Nitrogen toxicity from feeding too often or too much, or both. In soil it is plain water/plain water/feed/plain water/plain water/feed, so that the plants are being fed every 12 days or so. Feeding every 3-4 days in soil is waaaaaaaay too often. Soil "holds onto" nutrients more so than other types of substrates and the plants need to use what is there first, before any new nutrients are added, otherwise you gey nitrogen toxicity, just like your plant. Also, never grow at 24/0, your plants must be exhausted by now! All plants NEED sleep to finish their photosynthesis cycle and to have a correctly functioning metabolism. A plant with an incorrectly functioning metabolism will never grow to its full potential. The myth that it is ok to grow at 24/0 needs to be removed from history and could only be recommended by people who don't understand photosynthesis or how plants function either. The good news is that it is never too late to go to 18/6, which is optimum. Besides, cannabis can only grow so much during any one 24 hour period and this growth tops out at around the 18 hour mark, meaning running your lights any longer than 18 hours is basically a waste of electricity. If I were you, I would stop feeding my plants for 2 weeks and give them only plain water in normal amounts and at normal intervals, before resuming feeding with half strength nutrients. Flushing your pots with huge amounts of water can lead to even more nutrient salts (which is the cause of nitrogen toxicity) being released from the soil, which will then cause even more burning! So, to sum up, switch to 18/6, give just plain water for 2 weeks, go back to feeding after this with half strength nutrients, and most importantly, always water with plain water between feeds........ For soil it is ....... plain water/plain water/feed/plain water/plain water/feed........so that they are only getting fed every 10-14 days. Hope this helps, Organoman.