dozer, I use a quality organic potting soil. I start in cups, 5-8 oz. size. As the plant grows, needing more root space, I up-pot into 1/2 gallon pots, then into 2 gallons. About 10-14 days prior to inducing flowering, I repot into 5 gallon pots.I use FF "grow Big", 3-5 times over 4-5 weeks of vegging and probably twice during the first cpl weeks of flowering. I use FF Big Bloom and Tiger bloom, in unison once a week for 5-6 weeks of flowering. I use fresh new soil in every uppot, and I never "leech".
If, you do find it necessary, you can run 3-5 times the amount of water as your pot holds, through the medium. Pour it in the top, let it slowly drain out the bottom. ie...a 3 gallon pot will require around 9 gallons