In mid-MD I maintain two OHs. One at Earth Space & Science Lab. One at a Nature Center. Single layer. Shallow frame over three deeps.
I have never treated for mites. The ESSL swarms every year. Intentionally. I had a couple extra Apivar strips the other day, so I added one to each of the hive entrances. Shown is the very strong ESSL and its entrance. Do you treat for mites somehow? If so, what technique do you use?