I saw a post on Facebook where someone said they had success with using 1 sugar cube / 12 bottle carb. Sugar dots is what he called them Anyone here tried this? I wouldn't have thought they would fit.
It seems to be working for some people: https://nebrewing.wordpress.com/2014/09/08/bottle-priming-with-sugar-cubes/comment-page-1/ I don't acutally have any sugar cubes, but they should be 1cm ^ 3. Eyeballing it, I think they'd fit. My bigger concern would be that it wouldn't be the carbonation level you'd want. 1 cube being too little, and 2 being too much. Let us know.
You think ~2.5 CO2 volume is a little low? I don't measure CO2 volume / bottle carb very often, so I don't have much of a frame for reference.
My back of the envelope calculation says worth a try but don't expect perfection. I suspect that @inchrisin has it right. Maybe one cube for English beers, 2 cubes for Belgian beers, and in between for most others? Best way to prime bottles IMO is to use a priming calculator, weigh out the sugar, dissolve the sugar in a small volume of warm, heat-sanitized water, and gently stir the liquid into your beer in your bottling bucket.
I too prefer to add priming sugar (or table sugar) to the bottling bucket. My method is to boil a small volume of water, mix in the sugar by weight according to a priming calculator, dump it into an empty sanitized bucket. Then rack the beer onto that - it gently mixes itself.
I use sugar cubes if I am just bottling a few. If the whole batch is getting bottled then I batch prime. Works great if you are going to do something like bottle a six pack at the end of primary and secondary the rest. I've never done the math but my mouth says it carbs to maybe 2.5 vols but no more. Regular Domino Dots fit fine down the neck of a 12oz bottle.
You might be able to get a little more precision on the carbonation level using sugar tablets like these instead of sugar cubes. Their directions specify 3 tablets for low carbonation and 5 for high. https://www.amazon.com/Brewers-Best-Conditioning-Tablets-Count/dp/B006O2D9RE
I use the Domino dots for bottle carbing, and I have been very happy with the results, which have been much more consistent than when I was using carb drops. 1 cube fits easily in the neck of standard bottles (they don't fit quite as well in some bottles with thicker glass and in some foreign bottles). A single cube gives me medium carbonation. You definitely would not want to use 2 cubes in a 12oz bottle. If I'm looking for a higher level of carbonation (like for saisons or other Belgians), I supplement the sugar cubes with 1 of the sugar tablets mentioned in the post above.
My back of the envelope calculation was 1 cube = half a tsp. The generic recommendation for a 5 gallon is 3/4 cup sugar. 3/4=12 TSP= 36 tsp. That would be 72 cubes per 5 gal batch which would be 1.75 cubes for 48 bottles. Yeah, you might get 52 bottles out of a 5 gallon batch, but that would have required another envelope - long division is advance maths. However, a couple people say empirically that 1 is enough and 2 would be too many, so ignore my earlier comment about using 2 for Belgians. Once I started weighing out sugar, I decided that 3/4 cup was too much anyhow.
