Not enough sugar for bottling?

I've tried this same method now for 3 batches and I'm not having much success with carbing. 1 in 10 bottles has a little carbing but the rest are flat.
One... That makes me think maybe something was uneven but secondly, I'm wondering if I'm adding enough dextrose.
I add:
1/8 cup dextrose per gallon of cider
OR 3/4 cup dextrose for 5-6 gallon carboy (jug)

Is this enough?
I also add sulphites at bottling. I'm wondering if that is hurting the yeast.
I use a measuring cup to do this.

I use Grolsch style bottles (Hacker Pschorr beer) so what is the maximum pressure they can hold? Assuming the cider I'm doing is around 2.5 co2 when bottle carbed.

 

Jeeze, I would think so. Don't wine makers use sulphites to stop fermentation prior to bottling?

3/4 of a cup of dextrose is in the ballpark for carbonating a keg of beer (probably a tad on the heavy side) so I don't think that's your problem.
But if there's no yeast to eat it...

Cheers!

 

Dunno. I was told on this forum to add sulphites at every other racking and just before bottling. Assumption was it only slowed the yeast not killed it. The sulphites were necessary to stop oxidisation.

 

+1 for going by weight, not volume.

How long are you waiting for them to carbonate? It can take up to 6 weeks.
What temperature are you keeping the bottles while carbonating? Room temperature well help them carb faster.
How long is it fermenting? Bottling sooner after it finishes will carb faster since the yeast is more active. ... And there is more residual CO2 in solution.

Here's what I do: Use a priming sugar calculator to determine the weight of sugar. Dissolve the sugar in hot/boiled dechlorinated water and put it in your bottling bucket before you rack in the cider. Gently stir to mix.

I don't know about sulphites but I trust Yooper

 

Primary was about 6 weeks.
Secondary 3 months since it still had bubbles.
Bottled and left for 3+ months at room temperature.
1 in 10 carbed.
Maybe there weren't enough yeast nutrients...I don't normally add them at fermentation.
I've had this every time I bottled.
I fill just up to the thin neck of the bottle - should it be more?

 

Fermentation is basically finished in around 3-14 days. The bubbling after that point is the cider losing carbonation. In secondary that long it will pretty much lose all carbonation.
About a half-inch to an inch of headspace is considered ideal.
I don't use yeast nutrient, so I doubt that is an issue, although not all juice is the same.

My guess is that you aren't using enough priming sugar. Go by weight and add an extra volume since it lost all the CO2 from fermentation.... around 30 grams per gallon should be plenty.
You could also consider reducing the bulk aging time so you have more active yeast when bottling.

Cheers

 

It sounds more like I'm not moving to secondary quick enough and leaving in secondary too long. I wait until all bubbles have stopped. Agree weight is more accurate but a 1/8 cup of powdered dextrose is going to be pretty close.
Should I time bubbles in secondary instead?

 

It sounds like it's sitting so long that you have no active yeast to carb.

 

I thought they woke up again on addition of sugar?

 

I made apfelwein that's been bottled a bit over 2 weeks this past weekend and had one. It wasn't that carbed at all. I think my basement is a bit too cold. I'm going to move them upstairs where it's warmer and see how they react.

 

Edit: deleted

 

Well, I'm no microbiologist, but here's how it looks to me. You think you have enough sugar added but it's not carbonating....ergo, nothing is eating the sugar.