Hey I'm a fairly new grower,I'm using FF dirty dozen,I have 7 plants in soil in 5th week flowering under 400hps,marshydro TS 1000&tsw 2000+ 105 watts 4200k cfl,my runoff ppm is higher than my nutrient solution,plants look fine and I'm debating preflushing or should I wait until week 7 or 8 to...