Have an infected batch.The infection has showed up as milky white film with the odd bubble that breaks up into white plates when disturbed. wort was fermented with white labs Notingham strain,cleared up at about 7 days,top of beer clean as a whistle at(to the naked eye anyhow) about 10 days.Went to rack at day 16 and infection sighted.seemed to flair up overnight.i am wondering wether the bug has been introduced at a later stage(tho fermentors been double cling wrapped and undisturbed) or more likely allways been there and just showed up with less c02 present.the only other infection ive had i put down to opening up for dry hopping.if youve had a infected batch how long into fermentation have you noticed it?