For example, cutting edge solution has nutrient calculator which tells me how much to feed the girls. You dont want to give the full amout(you put the girls in shock). So I take the number(In Veg stage it say to have 1400 to 1600ppm Cutting Edge Solutions) & divide by 4. So for the first week I only add a 1/4 of whats recommended. Second week I add 1/2, Third week 3/4 & fourth week, what it says. Then I go back down to 3/4 then 1/2 then 1/4. By that time its time to flush your girls.