Yellowing leaves with brown spots

Cheers, mate. First of all please give some informations about the week that you are and mostly if your grow is a photoperiod strain or a automatic strain, so if you are already on flowering stage, by the photos and not knowing the week that you grow is passing by, the almost complete yellow leaf (just in case that you are on flowering) is a pretty normal process of maturing. Probably the yellow leaf should be a leaf on inner areas of the grow and if this is what is happening the yellow character is linked both to the grow cycle is coming to the end and probably this leafs are in inner areas of the grow so areas without complete light exposition. Without knowing both the week of your grow and if you are already on the final weeks of your grow, it is pretty normal to have yellow leafs and that doesn't mean that you have some deficiency. Even if you are still on vegetative phase it is pretty normal to have yellow leafs on the lower areas of the grow and that represents that the older leafs, naturally turn yellowish and tend to fall. As I tell you by my experience there isn't any problem (deficiencies or plagues) linked to your yellow leafs. It will be a problem if all of your growth became yellow, but mostly and regarding your photos, the leafs that you are showing are simple the older leafs on the grow set and it is perfectly normal to have some leafs that along the time get yellow, mostly the older ones. So don't worry about that and you should be worry normally if the leafs over the top of the growth start to show brown dots; if the leafs start to get curled or bended or if you clearly start to see a fast progression of dehidrated leafs. Normally this symptoms are linked to deficiencies or to plagues, but a regular full yellowing on all the leaf surface mostly represents the normal aging of the leafs or the indication of the plants cycle going to its end. So don't worry much about it