We can work it out...

...or can we?
Back to 'Craft Cider Making' we learn to add 10gms per litre (or that 'flat teaspoon' per pint)
Work that one out - clearly my teaspoon just isn't big enough...
It should be bourne in mind that we are not after cascades of bubbles - no gushing - no disturbing of sediment. Just a gentle 'psst' and those lovely Co2 bubbles gently rising and adding a little zest to the conditioned cider.
Seems the Whitworth cubes (at 3g) could be on the small side though, but these could be saved for batches with a slightly higher SG - say 1.003.
Batch 10 was all bottled on Sunday with an SG of 1.001 adding a single 4g SilverSpoon sugar cube (slightly less as a little is lost in the act of halving it)
It should be noted that the Whitworth cubes do tend to dissolve more quickly than the Silver Spoon - though after capping a quick inversion and swirl does the trick, again checking at labelling time to make sure all is dissolved.