I see you're getting heaps of advice on the coop side, but a few notes for the brooder...
Chicks produce a lot of feather dander at that age. Choose a location that you won't mind getting a bit dusty.
At 3 weeks, chicks are starting to become a bit hardened to the cold and depending on the ambient in your room of choice, you can likely get away with some less intense heat options. At that age, a seedling heat mat may be all they need.
My recommendation for day old is to go with a caged ceramic heat fixture and ceramic bulb (not a red bulb unless you have major low temps to combat) on thermostat, but if you have no intention to ever get them this young, the former will likely get more use if you have to quarantine a sick hen etc in the future.
The brooder... Smaller spaces are good when trying to maintain heat, but the brooder needs to expand with age if you don't want a smelly mess. An xl fabric puppy play pen is great for brooding older chicks though hard for hanging a heat lamp without a custom built frame. The pet pen panels for rabbits etc are invaluable for making a quick pen indoors or outdoors. A good 6 panel offers 1200x600mm space. With my first brood, I graduated them to the panels with corrugated cardboard wrapped around them, bird netting stretched over the top and cardboard flooring. Make sure to elevate the waterer so it is not sitting on your bedding - paver tiles are really good for this. You want to avoid it getting spilled or soiled at all costs as this will likely be what makes your brooder smelly.
Another good advantage to puppy panels is future isolation when integrating and getting them outside early if the weather is nice and warm. I have a few sets handy.
Coccidia is everywhere in the environment. They need time to develop a natural resistance. Medicated feed or cocciprol in the water does just that, so do not skip it! Pick one and dose accordingly, but never double up as they will negate each other.
Keep to crumble - starter or grower till they're point of lay. They shouldn't need medicated past 6-8 weeks. If you plan on keeping roos, you can keep them on grower and offer grit on the side, otherwise, you can move to a pelleted layer when they are close to lay.
Pelleted is recommended over loose grain for a few reasons... Top hens will hog the best bits which may lead to nutrition imbalances in lower birds. They will pick through for what they prefer, which can lead to food wastage as well. It is a bit more critical for production breeds, which can be pretty sensitive to deficiencies, but is good to consider in general.
In the run, it is good to have a dedicated covered dust bathing area which can fit all or most if your birds at once for parasite control that is protected from getting wet. - all of my girls enjoy a good dry bath when it's raining out.
Good luck! Brooder babies are very happy man friendly and make lively companions. You're sure to enjoy your little fuzzy top babies.
Chicks produce a lot of feather dander at that age. Choose a location that you won't mind getting a bit dusty.
At 3 weeks, chicks are starting to become a bit hardened to the cold and depending on the ambient in your room of choice, you can likely get away with some less intense heat options. At that age, a seedling heat mat may be all they need.
My recommendation for day old is to go with a caged ceramic heat fixture and ceramic bulb (not a red bulb unless you have major low temps to combat) on thermostat, but if you have no intention to ever get them this young, the former will likely get more use if you have to quarantine a sick hen etc in the future.
The brooder... Smaller spaces are good when trying to maintain heat, but the brooder needs to expand with age if you don't want a smelly mess. An xl fabric puppy play pen is great for brooding older chicks though hard for hanging a heat lamp without a custom built frame. The pet pen panels for rabbits etc are invaluable for making a quick pen indoors or outdoors. A good 6 panel offers 1200x600mm space. With my first brood, I graduated them to the panels with corrugated cardboard wrapped around them, bird netting stretched over the top and cardboard flooring. Make sure to elevate the waterer so it is not sitting on your bedding - paver tiles are really good for this. You want to avoid it getting spilled or soiled at all costs as this will likely be what makes your brooder smelly.
Another good advantage to puppy panels is future isolation when integrating and getting them outside early if the weather is nice and warm. I have a few sets handy.
Coccidia is everywhere in the environment. They need time to develop a natural resistance. Medicated feed or cocciprol in the water does just that, so do not skip it! Pick one and dose accordingly, but never double up as they will negate each other.
Keep to crumble - starter or grower till they're point of lay. They shouldn't need medicated past 6-8 weeks. If you plan on keeping roos, you can keep them on grower and offer grit on the side, otherwise, you can move to a pelleted layer when they are close to lay.
Pelleted is recommended over loose grain for a few reasons... Top hens will hog the best bits which may lead to nutrition imbalances in lower birds. They will pick through for what they prefer, which can lead to food wastage as well. It is a bit more critical for production breeds, which can be pretty sensitive to deficiencies, but is good to consider in general.
In the run, it is good to have a dedicated covered dust bathing area which can fit all or most if your birds at once for parasite control that is protected from getting wet. - all of my girls enjoy a good dry bath when it's raining out.
Good luck! Brooder babies are very happy man friendly and make lively companions. You're sure to enjoy your little fuzzy top babies.