Leaves still getting yellow/brown

If you need any other help with this hit up your DM's Your inbox is the little green arrow on the bottom right hand corner. Good Luck!

The size of the pots is ok, when they grow in the ground as in nature, they have acres of room for root growth. The lighting at 18/6 is perfect. Lights at 30 inches maybe a tad too far away, about 24 inches is better. No fan is no good, they need air movement to be able to transpire properly. All your pictures look like a much too wet substrate, water only once the top 2-3 cm have dried out completely. The damaged leaves will not recover, but your new growth should be fine. Add a fan, reduce the watering, decrease the light height and start feeding more regularly, with half strength and things should pick up. A dose or three with some seaweed tonic/extract would also help them recover. Remember too, you are on a new adventure with growing and to get familiar with what it takes, takes time. Hope this helps, Organoman.

I don't know if you saw or followed my last answers advice but same thing works here, I'll reiterate, BioBizz nutrients work best with a PH of 6.2, going lower can cause issues even if it is in coir. Also with BioBizz it should sit out over night, its PH drifts down and you may not need to use any PH down after letting it sit. If you coir substrate was not buffered or rinsed before use it will cause problems for you. growdiaries.com/journal/how-to-grow-cannabis-in-coco-coir this article touches base on the aspect of rinsing and buffering coir. Use this link for a feeding guideline based on EC, its not 100% so if your plants need more or less listen to them and adjust accordingly. https://www.autoflower.net/forums/threads/med-man-method-feeding-chart-ppm-ec.47856/ If you are using Liquid feed and do not have a TDS pen it might be time to get one. It is a great tool to help you find out what wrong with your grow if something goes wrong. Be careful of upping CalMg, it has a high EC and can throw your medium out of wack, autos are very sensitive to changes in the root zone. Doing a great job on keeping the temps and RH in check. Good Luck!

I think the biggest issue you have is over watering. Need more coco or perlite in substrate in future grows if you have a heavy watering hand. Soil needs wet and dry times. At this size you sound only water about once a week. Maybe twice depending on how wet you get it. I water in sides taking turns so half the substrate stays drier when doing soil.

Them leafs at the end brother are from your last mistakes, they won't change with all the magic in the bud world. Increase ur cal mag. And other grow question was right too pots that big you should have a root stim and a micro, kinda defeats the purpose of growing in big pots if you aren't gonna stim youe roots. Yeah, increase cal mag. Get some basic npk grow and micro and you'll be laughing Amazon do a good trio for 18$ of general hydroponics or Advanced Nutrients are cheap. If you g9 with AN. Get vood0o+tarantula+ piranha this will deal with micro enzymes root stim and tarantula is both and also helps break down and root rot which you might get growing in soil and over watering. As for it now with what u got. Increasw cal 1.5-2ml/l and get some basic grow+bloom+micro if you already haven't got bloom. And if you wanna go all in for a few extra bucks get the AN gear it's great. Hope this helps.