Start using Biobizz nutrients when your plant is 10-15 cm tall or has 2 to 4 leaves. Continue using the products up to 1 to 2 weeks before harvest, following the official Biobizz feed charts.
Biobizz recommends adding the products every time you water your plants (about 1-3 times a week). Otherwise, you might be getting different EC/pH levels since your plants will need to adjust every time.
It depends on the nutrient brand. Some are every feed others are once a week. Most will do a water,water,feed,water,water,feed. Always water and feed until you get a little runoff to avoid buildup.