Newbie Cider Ferment Please Help!

[withgusto11]

Hi There
I am having a go at my first brew of anything alcoholic - using up our apples (unknown seedling variety) to make cider.
I juiced the apples using a juicer (until the juicer melted), then blended the remaining apples and had a go at pressing them using a car jack, milk crate and wooden frame. Ended up with a 5L demijohn (all from the juiced apples) and two 1.25L PET drink bottles full of juice (mostly from the crushed and pressed apples).
I should say that the apples weren't all fully ripe, I was trying to beat the fruit bats, fruit flies and rainbow lorikeets. When I tasted the apple juice it was, however, delicious.
I bought myself a hydrometer to measure SG but it turned out to be a beer hydrometer so it only went up to 1.050. The juice reading was higher than this... That is to say, I don't have an accurate reading OG for the apple juice.
I zapped the juice with sodium metabisulphite for 24 hours, then added Vintners Harvest SN9 yeast - just sprinkled it on the top: 0.5 tsp for the demijohn, a pinch for each of the PET bottles.

Each PET bottle has a grommet and fermentation lock in it, the demijohn just has some muslin over the top as our local brew shop is out of bungs, hopefully pick one up tomorrow.
So I put the yeast in on Tuesday night. Saw signs of yeast action yesterday (Wednesday), thought it was all going well. Then today it looks like the yeast has finished in the PET bottles: one has a little foam dome on the top, the other has traces but nothing much at all. Neither has had any bubble action in the lock.
I gave one of the bottles a squeeze to try and see if it was airtight but ended up backwashing a bit of the water from the lock into it... Oops...

The demijohn, in contrast to the PET bottles, seems to be going along okay - there's a bit of foam on top but, of course, no airlock so I don't know if it is bubbling along...
So I guess I need to ask some questions:

1) if the yeast cap on top of the liquid in the PET bottle is breaking up and not increasing, is it dead? Is it possible that there was very little sugar in the juice and the first ferment is finished in 24 hours? Without producing enough gas to bubble through the locks?

2) Is not having an airlock on the demijohn at this point a problem?

3) Is the backwashed bottle dead or could it still be okay?

4) If the yeast has finished, should I add sugar and more yeast to try and remedy it?

Any answers, advice or friendly roasting welcome.
Cheers!

 

[manticle]

Take a gravity reading.

 

[mikesnothere]

For starters, I pity the brewer that never makes a beer with an OG over 1050.

1. If you put the same yeast in all three bottles, it won't be dead in two and going strong in one. Most likely vigorous fermentation is over or you don't have a perfect seal.

2. It's not great, but time will tell. Glad wrap is probably better than muslin. Even if it just sits on top loosely, it'll stop any nasties falling in.

3. should be fine, but again, time will tell.

4. Only add more sugar if you want a stronger cider. You won't need to add more yeast.

And as Man Tickle said, take a gravity reading.

 

[withgusto11]

Thank you both. I bought a new hydrometer today and measured the juice from one of the bottles and from the demijohn. There was a significant difference which I put down to the fact that the demijohn had apples juiced that had been sitting for at least a week, the PET bottle batch was crushed and pressed, less ripening for the apples.
The PET bottle read at 1035, the demijohn read 1045. These readings were taken almost three full days after the yeast was added.
My guess is that there is enough sugar to get the primary fermentation done?
I finally got a bung with a stopper in it for the demijohn.
Any further advice or pointers gladly received.
Cheers!
Edit: here is a picture for your critique...