Sup guys! I am having this issue and i cannot pinpoint exaclty what is wrong...maybe someone had similar issues and can help me out. I am growing Fast Buds autos, Crystal Meth and Northern Express. I am currently at day 22. They have been having these spotting, yellowing and drying issues on bottom leaves for a while now. When it first started i thought it was magnesium def since i use RO water so started watering with epsom salt.....but no joy. I now think it might be potassium def but I am unsure. I am using biobizz nute line, currently at 3/4 strength with bio-grow alongside bio-heaven (2ml). I was thinking to water with some bloom fert to increase potassium but I am unsure. Any input will be greatly appreciated. Here are some pics of how it progresses:
Cheers
Cheers