To not spread the infestation to other parts of the garden (clone area, mother plants, sprouts, rooting cuts, etc....) mighty wash was the best option here imo. I mean what if the op decides to run longer due to his/her plants not being fully ready. I have heard about the co2 thing. Others on here have stated that that is simply not true, personally i don't know cuz i have never tried it. Personally though i have sprayed mighty wash at week 7 on a 9 week strain and felt no quality was lost. Totally respect your post and advice. The op will tell us what his/her findings are I'm sure. Merry Christmas.