first dwc grow/ how much nutes should i buy?

im a newb. im gonna be using a 50 gallon rubbermaid to grow six plants.. im looking to buy nutrients and dont know much about them.. im thinking about going with the foxfarm trio but how much should i buy?

or reccomend any other nutes? and how much should i buy for those that are reccomended?

i use general hydroponics...theyve lasted my whole grow so far...next time i will buy a gallon of each though its cheaper

I bought the Technaflora starter kit but am opting for a switch to the gh maxi line because it will be easier and much cheaper. flora should be goood too but I want to use dry nutes they're easier to manage.