Firstly , maris dont hijack threads mate it confuses people and is very rude, we will deal with you later.
Now your problem(letstrip) is salt burn. It causes the rust spots, upper and lower shade leaf yellowing as the plant can no longer take up N and other trace elements. The rust spots are burn spots.
Its the crap woodchip soil your using that you get for $2 a bag at the supermarket. Next time use a pro growers coco mix that is $40 for the same size bag from hydro store and you will have green leaves top to bottom start to finish
Also letting the pot dry too much encourages salt build up /burn.