I got the tank at a paint ball store. I refill the tank at $2 per/fill about every three months. At 200 per/week you will probably have to fill about once a month. You will also need a larger kill tank. That one will do about 10 mice per load, it is too small for adult rats.
I am supposed to be writing up instructions to go with the pic of my set up for a friends web page. I will try to get around to it sometime this week.
Meanwhile, I hope the pic helps, it is pretty self explanatory. CO2 in bottom, exaust on top. You need a bigger kill tank than mine.
