They are rubbermaid for the most part though I have a couple of heavy duty tubs that were given to me and don't have a brand name stamped on them. These are from Walmart. I think 2 of them are 100 gallon, 2 70 gallon, 2 50 gallon, and I have 1 30 gallon that I use for small hatches.
The chicken pen is 3 ft by 8 ft by 3 feet high with a door that opens in the middle so I can reach to either end. It is 1/2 inch galvanized wire mesh with a wooden framework. I can put up to 150 chicks in it at a time so long as they are no larger than a 3 week chick. I start pulling out the larger chicks around 6 weeks. It is very important to have 2 or more heat bulbs with this setup as the chicks will pile up which can kill them. With multiple bulbs, they spread out.
There have been few problems with predators. I lost a couple to a fox and a couple of young chickens were taken by a hawk so far this year. I can ignore losses of 4 birds.
I feed 27% to chicks (chickens only, turkeys get 30%) and 22% to hens that are not laying. When they are laying, I feed all they can eat whole kernel corn along with 30% feed as much as they want. I could increase chick growth rate a bit with higher protein feed, but it can be counterproductive with large fowl chickens. They can grow faster than I like which affects their body shape and feather colors. For laying chickens, the common 22% feed is not good enough IMO.
I bred a high protein corn a few years ago that I love to feed to my chickens when I have it. I put 5 gallons of corn in a bucket and fill it with water. Two days later I pour it out for the chickens. The chickens gobble it up like candy. This corn is high enough protein that free range chickens increase egg production about 10% as compared to 22% commercial chicken feed. The reason is that my corn has much more natural methionine than any commercially available hybrid corn.