How are you growing her? Most hydroponics only need flushing for a week or so, thats usually the last week right before chopping.
Flushing hydroponically - Ideally swap your nutrient water with clean RO water for the last week, a quick flood to drain of the roots would help too.
Flushing in soil - From what I've read, flush with water 2-3 times the size of your soil (so i guess if you are growing soil with a 5 gallon bucket, then flush initially with 15 gallons of clean water) with 3 weeks left and instead of feeding her normally for the last 3 weeks just give her clean water.
So if you have a 10wks to flower strain, your scenario would be this -> change lights to 12/12 (after your veg cycle) she'll start to flower within a week or so, AFTER she starts to flower then you have 10wks of flowering, you'll put her on a regular feeding schedule for the first 7wks (soil) or 9wks (hydro) then for the last 3wks (soil) and 1wk (hydro) start your flushing process and end with giving her clean water. Your fan leaves will start to yellow these weeks because of it.
As for the lights, I have no idea, sorry dude.
-V