it really is the key bro,with this and ph npk testing anything wrong you got to stoned hahahah,i been on these sites for 10 plus years,one thing i know that when folk ask for help,most dont even know what they got,take bag soil,right there your down to 2 more chances,because it is a chance with them,testing every 3 or 4 yrs and all you do is water and get fatter,i swear oither night i got the munchies,ate at least 40 of them grape tomato's woke up to flying shits hahahah .
thats why i say doesnt matter medium you use water or soiless or soil all require same intake,you have to know what keeps them happy and testing does the trick,like insurance but only cost about 12 bucks for a kit and on amazon a basic soil sample test is about 25 bucks,for a full break down of cation exchange and all the goodies along with that a test every 3 or 4 years for a 100 bucks is worth the trip for me,my kids and grand kids kinda depend on old pop pop for veggies,which is weird,my 7 yr old grand baby loves brocille,squash,califlour,shit my mama beat the hell out of me to eat veggies as a kid hahahah,i do it for them,me i just like green leaves growing every were even my medicine i love seedling and veg,when flower come on plants are ugly to me lmao