and get a ph meter and some ph up and down. use these to test your water and adjust the ph. 6.2-6.7 is what you are aiming for. also, when the time comes, ph your nutrient solutions.

also, i would recommend getting some fertilizers especially made for weed. a good three part should be all you need.

what is a three part you ask?

well, they are micro, veg, and bloom nutes.

they all have varying levels of the major nutrients (nitrogen, phosphorous, and potassium, or N-P-K) and the micro has the trace elements.

you will read that for the vegetative growth cycle (18/6 light cycle) you will use a... well i think it's in one of those links i sent you in your other thread. peace