I don't really know how to heft. This means that I've been concerned about the stores in a couple of the hives for a few weeks. Today I visited and put some honey in to feed them. They honey had set to a stiff paste or fully hardened.
I took a super which had empty comb. I removed enough frames to fit 2 tubs and a jar. I then quickly popped the lid off; placed the super and honey and put the lids back on.
It's said that a colony never freezes but it can starve. It all comes down to stores. This is an admission that I probably took a bit too much honey from them. I wasn't intentionally greedy but the colony may have put stores above rather than adjacent to their brood frames. That would have left them lighter than intended.
I didn't have a spare super to sort out Hive C. I'll take one up and add some honey in for them soon.