I have 3 plants that have been in veg for 5 weeks now. I am ready to send them into flower stage & dont want a nute lock-out. I'm growing in hydro, I'm using the nutes that came with the kit. I'm still on my first grow & dont want to mess up so close to the end. Do I have 2 flush or just add new water with nutes &put on 12/12?