first
(yes) they can be added together you also want some tarantula they create symbiotic reaction when all 3 are together piranha/tarantula/voodoo juice feed them the first 4 week of the plants life then another 2 weeks at the beginning of flower . These products used together will boost your nutrient uptake , your root mass by over 800 % and some of your plants resistances to stuff like heat stress and for the lemon buy a proper PH meter some are cheap you can add lemon juice to your air-rated water but you need to know what are the original PH