I don't soak my beet pulp longer than a few minutes, same amount of water plus she won't eat it if it sits to long. She is a very picky horse.
The outside tanks have heaters so no ice out there. I should be getting a report soon if she has drank anything over night.
I will try heating some water in the microwave tonight to see if that helps. And changing out the bucket.
She used to also be on red cell which made her thirsty so I don't know if because she doesn't get that anymore that she doesn't want to drink as much. So I will be adding salt to her feed for now. She has a salt lick in her stall and outside too.