It's hard for me to say how many you need. It depends on your ppm of co2 in your ambient air. Since you probably don't have a meter (I know I don't) I would say at least two. More won't hurt. And yeah, your containers are fine, it doesn't have to be a milk jug. I'm just cheap like that. The only jugs I've ever bought are the ones on my chest. LOL!

Sending you girl vibes for your unknown clones.