well did u soak your hydroten? thats usually what causes maddd ph flux.check every day to make sure its not happening again. i check in the morning and at night as well as checking the ppm once per day.since your in dwc if u keep your ph right the hydroten will soak up that ph number much faster than other systems.ive been battling this flux for almost a month with a top feed drip.what a pain in the ass.