Question about multiple litters

I have a female that dropped 12 babies two weeks ago. They are just entering their hopper stage. Well now its 11 since we have one baby to the corn snake. :)

My question is, what size tank should I house her in while she nurses these 11 babies up until weaning age? Also, she's showing signs of a second pregnancy and I suspect her to be in her second week as with her first litter, she started getting large in the second week and really ballooned out the third week. Will it be ok for her to have her second litter around the same time the current litter is hitting 3 weeks?

Generally most people like to give the mother 3-4 weeks off (depending on species) to put some weight back on and regain some minerals and such so it won't be so hard on her. I'm believe she will be fine but she will need a longer rest afterwards to re-coup after that. Also you may want to try and adopt some of them off to another nursing female if you have one to give her a break.

She is a mouse and I do harem breeding. There will not be another nursing mother during the time that she has the babies as I'm just getting my colony started.

She'll be fine, since the babies wean around day 21. The cycle is a bit hard on them, and lessens their productivity time quite a bit, but it's still natural. I find harem trio breeding to be the best, since the dad also helps out and takes excellent care of the little ones! My two girls had their litters two days apart, so I have 18 (down from 20 :D) little hoppers running around with their parents, and both girls are getting pudgy again. By the time they're ready to have second litters, the first babies will be separated into the male/female tubs.

As long as you can keep track of dates and pull the weaned little ones out, there shouldn't be any problems.

They will be exactly 3 weeks old as of Sunday and I just weighed the female and she's gaining a lot of weight again. She's up to 48g from 35. when she had her first litter she went up to 51g and dropped 12 babies. So Sunday I will move the hoppers to the feeder tanks and let the female have her second litter without them scampering around causing mayhem.