I last filled up on Friday lunchtime and here I am on Monday evening adding another 3 liters or so. About 3 days!
They're putting it somewhere, I know they are.
Actually, this is good stuff as all the bees that were out foraging seemed to be brining in pollen - yellow; so ivy? - the frames are filling and both hives look quite strong now.
I'll continue doing the feed as I'd like them to draw out some more comb before I call it quits for the season.