Re: What are the advantages/disadvantages of 3 deeps?
My brother-in-law uses three deeps up in Michigan for a two queen setup. I believe he puts a spacer and queen excluders between the top two boxes with a queen above and below. After they build up with bees earlier in the session he removes the separation and the bees merge for a large colony. In his colder climate with less good weather for forage he likes to buildup the colony more quickly. Think you could do the same if using two pieces of screen on either side of a 1" thick square frame.
To answer your question more directly three deeps used for a two queen system would add the advantage of building up the colony more quickly while allowing the lower portion of the colony to help heat the one above.
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