I'm going to be growing two plants with a 150watt HPS and two CFL's. I'm going to use a DWC system i made out of a old rubbermaid. I already have an air stone, tubing, ph test kit, air pump, and the rubbermaid. i have the lights also I'm going to the hydroponics store that is about an hour away so i only want to make one trip. I have on my list- nutrients(how much should i get?) mesh pots rockwool grow rocks ph down/up EC meter??? This is my first time growing hydroponically and i don't know how much nutrients i need for the whole grow. and i'm wondering if i need a EC meter, i know it is important but i'm kinda on a budget to spend only like $100.