Upgrading my breeding colony with a few questions

[Sanibelfire]

I have 6 rack columns with a capacity of 35 tubs, currently only 32. For two years I have been breeding ASF and rats for my snakes but the ASFs started to not be enough for my snakes. I've decided to switch almost all of my tubs to rats. My plan is to run 1.4 in 30 tubs. Im going to build a birthing rack with 30-45 tubs depending on advice I get here. My main questions are how many birthing tubs will I need if I have 120 breeding females at 1.4 or 150 breeders @ 1.5? I plan on keeping two females in each birthing tub. I also have a two tub large grow out rack that I can add a level or two to if needed. Also if you have a good idea of a system like this how many do rats do you estimate I can produce per month with these numbers?

[Skilla6000]

Too be honest, if you're going to be running 30 colony's of 1.5 you should just make a 80 bin birthing rack or 2 40 bin racks. You also have to remember you're going to be producing 2000+ rats a month. You're going to have to get a bunch more grow out bins if you're going to go all out with this project. I would suggest at least another 20 bins just for grow out.

[Skilla6000]

So too make this short,

Two 40 bin birthing racks

20-40 grow out tubs.

[Sanibelfire]

I have to respectfully disagree with your estimate of producing 2000+ rats per month. The way I figure if females are pregnant 23 days and I wean at 28 days, assuming the females are immediately impregnated when put back into the group, it will be another 23 days till she gives birth again. Thats a turnaround of 74 days. If I retire females after a year of breeding that gives them right about 5 litters per year. I'm going to go with an average of 12 rats per litter, that gives me 600 rats per month. Of course I could be wrong about any of these figures thats just the math I am doing.