When i first started brewing i used to use a glad wrap lid and throw in a hydrometer. I was so paranoid about infection that i didn't want to open the fermenter at all.
With ag i don't use one, just give it a week and then a day or two at 20, then drop to 0C
With ag i don't use one, just give it a week and then a day or two at 20, then drop to 0C