The Corid won't negate the medicated. They're both thiamine blockers and likely both amprolium so rather than negate, it will be double dosing in effect.
Most recommend a heavy dosing of Corid to fight coccidia and some do so on top of the medicated.
However, I've read directions on a bag of medicated that said not to use it if also dosing with amprolium.
Mine is almost big enough to walk into. I think it was overkill. I started with a shelving unit my son was throwing away and a square multi tiered adjustable table. My thought was to make it big enough to incubate 4 levels of everything up to and including ostrich eggs and even for that, I think it's too big.
The overall dimensions are 40" high, 31" wide and 24" deep. I incubator part is 28" high, 24" wide and 24" deep. The rest is the hatcher portion, heat, humidity and air circulation area.
I think it has 80 eggs in it now that I set 3 days ago. In a couple more days I'll probably add about 30 more and the same every 5 days so I can have time to move each set to the hatcher.
I didn't get it rebuilt in time to make the Easter hatchalong but I'm making up for lost time.