The ratio totally depends on the size of the container... I use large cat pans, with about 20% more floor space than a 10g tank. My colonies can be anywhere from 1.3 to 2.7, each colony is different. Usually, if I leave a couple of females to grow up in a tub, I'll just scratch it, and start over, but that takes alot of time. Some females will accept a new addition, but not many. If I have a tub with only 3 females, but they produce like they're on welfare, then I don't touch it...