Hello and welcome to BYC!
Glad you joined.
Diluting the medicated with organic non-medicated is not doing you or the chicks any favors.
One brooder plate is more than enough for the number of chicks you have and I would never put a heat lamp on them in addition to the plate. I brooded chicks outdoors in the built-in brooder in my coop during a NY spring when the temps dropped down to 23F during their second week with one brooder plate with a towel tossed over it for 15 chicks. They absolutely thrived.
To build immunity, I give the chicks a chunk of sod (grass, dirt, rock, roots, critters and all) to the chicks starting in their second week. They will at first be terrified of it and will then have a royal blast scratching and pecking the clump apart. I replace it when it's too broken down and desiccated. THIS builds immunity.
However, I would ALWAYS have Corid on hand... just in case.
You need a coop with lots of high permanent ventilation and some coming in low. Leaving the space between the rafters open and paired with a gable and/or ridge vents works very well. All openings into the coop should be secured with 1/2" hardware clothe to prevent predators entering the coop.
Having an attached run with a solid roof and walls that can be covered with clear tarps to act as wind breaks is a HUGELY advantageous design for long snowy winters. This works very well:
View attachment 3094349
I use this:
I set it up on a large concrete block so it is about chest height on the chickens. It has kept the water thawed in temps into the -20sF.
I recommend running power to the coop and installing lights so you can turn lights on in the coop at night if you need them, run fans, the heated waterer, etc.
Thoughts?
