Mettcollsuss, on 12 Feb 2021 - 1:48 PM, said:
Yep, 16mm seems to be the standard. The length isn't as important as long as there's enough room for both the ants and a decent amount of water.
That's why 150mm is the perfect length. I've had 120 and the water ended in it in like a few months, I know it's a lot but I feel like if you will be keeping dozens-hundreds of colonies then you would probably have to change each colony's test tube every few days or just really often. And if you go for a longer than that, you'll get more cons than pros in my opinion.