most likely you will not need trace elements as the 3 part contains all of those trace elements, mostly in the micro. however, if you're water is fucked up, this might cause you problems. and by fucked up i mean hard water with lots of dissolved solids.
its hard to get a decent crop with GH3 parter without also using cal/mag plus. ive been using GH for yeras now and can really tell the difference when i use the cal/mag with it.
i dont know if the water is hard but hopfully it aint ok well i was gonna buy diamond necter but it costs a tone and dont have that much cash atm i think i will stay with just the gh 3 part as long as the pant wont die from it and then buy cal and mag or diamond necter if im feeling rich lol thanks all