I have decided that I will use apple juice to prime instead of pure sugar.

Here is my logic and my calculations to get my carbonation right. PLEASE point out any errors or mistakes or anything I have completely misunderstood here.

As far as my Cell bio knowledge tells me...my apple juice will contain glucose and fructose, which are similar sugars and both readily fermentable. (correct me at any time here)

My apple juice contains 10.2g/100ml of sugar.

According to a chart I found, my cider, at the average temp is is sitting at, will already have somewhere between 0.80 and 0.90 volumes of CO2 present.

I will, to try to avoid under-carbonation, assume that I only have about 0.83 volumes CO2 present.

I aim for a final carbonation value of 2.4 volumes CO2.

I have also learned that 4g/l of sucrose, increases CO2 by 1.0 volumes.

Now, sucrose is comprised of one fructose and one glucose bonded together. f I assume that, from a ferment point of view, glucose and fructose are the same, then I could also assume that by weight, if I had say 1g sucrose, 1g fructose and 1g glucose, they would all ferment more or less to the same values. So I don't need to make any conversion here.

So, I have 0.83 volumes and want 2.4. so I need 1.57 (lets just say 1.6) volumes added during carbonation.

1.6 x 4 = 6.4g/L

So I need 6.4g of sugar per L to get my carbonation where I want it.

My batches have 4L in them, but I'm going to lose a bit of that when I rack it for bottling off of the lees. lets say I end up with 3.75L in my bottling bucket.

6.4 x 3.75 = 24g sugar all up.

So I need 24 grams all up.

24/10.2 (g/100ml in my priming juice) = 2.35

So I need 235ml of juice in the bottom of my bottling bucket to end up with enough sugar to carbonate out to 2.4 volumes of CO2.

Sorry for such a long spiel. I just wanted to make sure I had it all right and sorted so I can make the calculations I need once the time comes.

Does anyone see any issues or holes in my logic here? any input or corrections would be greatly appreciated.

Thanks heaps in advance!