whats you water temps running,how often are you changing the rez?youve got pythium,totally saveable,but your gonna need to do some work,cheapest/most effective Ive seen is with compost tea ,but get your res temps in check first and keep them that way, Im betting your way over 70 in the rez,and cut out your organics if using them until its under control at least,I would go synthetic to save them,get a good yield,and yes Ive battled pythium many times ,won every time