FYI, if you put "cannabis deficiency" into google image search it will bring up the whole range of these sheets, may be of some use to you going forward
Big one on the left is the white rhino... and the small ones on the right are strawberry ice an the taller of the all is i think amnesia trance, using BioBiz all-mix soil an tomorite with sea weed extract as feed.
Yeah they just need a feed mate, i too am using just a bottle of tomato food and simply just feed everytime i water them with a weaker mix and it works out fine, saves having to remember if you have to give em water or feed every time lol