Trying something a little different this year.
I have used an old wheat bag to fashion a small, breathable bag to keep about 15Kg of rice on top of the brood box. It sits on a board on top of the frames with bee space all round.
I took the 2nd brood box off this hive to strengthen a very weak one. To compensate the loss off bees I am using this to 1. Use the rice to help de humidify and 2. Give the hive thermal mass on cold nights, a bit like the old wheat bed warmers.
As an after thought, I will be able to use it a guide in Spring for a super if bees start to build in this space.