seems like everyone and they moma got some free hijack or raft beans but me lol
First grow, DWC ... used gravity... added week 4 of flower (because I'm a newb). Ran it for 12 days at 1.5 mL/ gallon. Used 20% nutes.
Then I had 100% nutes, no gravity for 7 days.
Then I used gravity again during week 6 and 7, again 20% nutes. 1.5 mL/ gal on the gravity. Ran 9 days this time.
I saw amazing results from the second application (closer to when you are recommended to add it). My buds exploded and they are rock hard.
Start very slowly... you can always add more. Raise the lights to be safe... I raised mine, but found that I could keep them at the same height (400w hps + 250w mh 6 inches off the tips).
Good luck... if you do it right it should make you very happy.
Oh, and one more thing... After I messed up giving too early I wrote to Emerald Triange (makers of gravity) to ask what I should do. Phil (from ET) told me that many of their cutomers start using the Gravity week 5 of flower and run until the end... (and judging from his tone I don't think he was just trying to sell more gravity)