Brown area on leaves

I believe your plants are beginning to show stress signs from growing with constant 24/0 light, which is actually very unhealthy for your plants. Changing to 18/6 will allow your plants to get the sleep they NEED and return them to a normal metabolism and also allow them to have a proper photosynthetic cycle, whereby they will be able to do the things they NEED to do when in darkness and which they can not do during the lights on time. Everything on planet Earth has lived their entire existence of life, with sleep every day and cannabis is no exception, it is called a "circadian rhythm" and without one, nothing on planet Earth can function successfully and healthily. You will not lose anything by going to 18/6, in fact you will actually gain a benefit by doing so, as your plant will have a normal metabolism and be able to make healthy cannabinoids, something it can not do without sleep every day. Every plant needs a dark period to have a normal photosynthesis cycle and without darkness, your plant can not undertake certain processes that it can not do during the lights on time. 18/6 is not a random number, but a scientific conclusion drawn from 80+ years of cannabis research and has been found to be the optimum lighting schedule for cannabis, autos or photoperiod plants in vegetative growth. I like to think of the 6 hours of "sleep" as 2 hours to recover from the day, 2 hours to rest and 2 hours to get ready for the day ahead, and this is basically what happens during the "sleep" time and without the "sleep" your plant is exhausted, and an exhausted plant can not grow prime quality flowers. If you are keen, google "photosynthesis" and you will quickly learn why plants actually need sleep. Growing at 24/0 can only be recommended by people who do not understand how plants function and I wish people would stop saying "growing with 24 hour light is ok for auto flowers" as it is just not healthy or normal for any plant to be grown without sleep. I guarantee you will not lose anything by going to 18/6, only gain benefits and most probably find that all your problems will disappear. Hope this helps, Organoman.